The problem occurs all throughout the track.  It does it in both DC and DCC modes.  I recently cleaned the entire track, and my other Bachmann DCC trains and old Athearn PA's all run great.

I immediately had issues with a new GP40 with DCC on board.  Was very loud, and you would hit the throttle it would stall for a second, then jump.  And at anything but top speed it would run at very inconstant speed.  My other DCC loco ran fine on same track, so I know the loco was bad.  Anyway,  sent in warranty card within a week.  Within a few weeks sent loco back with copy of receipt.  I gave them my number and email, but never heard anything.  After a month began to wonder if they got it.  At 6 weeks, it finally came back.  I went to test it and...surprise, exact same thing.  They sent an invoice that said something about replacement GP40 DCC bla bla bla  N/C Ginny.  I have no idea what N/C means, but they obviously didn't fix it.  Does it mean Not Covered?  It was brand new and I sent warranty card AND copy of the receipt.  Its difficult for me to make a call during the day, so I emailed them 2 days ago and told them everything above.  And true to Bachmann form, I still don't have a reply.  I have never seen such poor customer service in my life.   At this point I have no confidence whatsoever it will ever be fixed by them.  Even if they do, it has already been 2 months and I've had to spend money to ship it to them once, and would have to do it again.  I know I'm not adding anything as this board is already full of Bachmann customer service horror stories.  But I'd be remiss not to warn others.  Oh, and by the way, the first time I contacted them about sending it back - I filled out the service request form three times on their website, then sent 2 emails and waited 2 or 3 days before I got a response.   In the last email I told them it was the 5th time I'd tried to contact them.  When they finally responded there was no "Sorry about the slow response..." or "We apologize for the delay in getting back to you..."  It was just "Send your loco to bla bla bla.  Here are the prices for repair bla bla bla.  If I was running a company that treated customers that way, I'd fire anybody who treated a customer like that

dapper d - is it on the starboard side?  I got a bachman gp30 and thought the same thing, but after seeing some pictures on the internet I noticed they were all missing the window.  turns out they did that on purpose in case you want to add an engineer figure with his arm hanging out. 

Ahhh, that totally makes sense.   I will give it a little oil and continue to break it in, except maybe I will limit the sessions to 45 minutes or so until I get it fully broken in.  At which point I imagine it would be less likely to bind or provide resistance to the motor?

I have the Nickel Plate Road GP30 DCC loco.  Got it recently and until a couple days ago only had about 30 minutes of run time.  The day before yesterday I decided I would let it run for a while to break it in.  I set it about half throttle and ran it for 3.5 hours straight.  It was very uneventful and I could already hear a reduction in engine noise.  The next night I figured I'd do it again.  But this time, after about 1.5 hours it came to a very brief stop, then took off again.  Then a few minutes later, it did the exact same thing.  Then again.  The stops are VERY brief.  As soon as it stops it starts again.  I put a lighted car on the track to see if the voltage was dropping.  Well the next time the loco stopped, the light did not even flicker.  The next thing I did was run my FT-A at the same time.   I did that for about 10 minutes but the GP30 never paused again.  I think I will try that again tonight.  My track is very clean (just cleaned it), and the pauses don't always happen in the same place.  Very strange.  It does seem like it has to run a while before it starts pausing.  Is there any sort of protection built into the decoder to shut down when too hot?  Even that doesn't make much sense because it can pause once, then not pause again for another 5 minutes. 
Guessing I might have to send it to Bachmann.  This would be 2 out of 3 locos I've had issued with.  The last one just flat-out died after about 3 hours of runtime (not even continuous).   Starting to think the Bachmanns are junk?

Well I got my decoder installed, but I dont have the replacement wheels yet.  I ran it to see what happens and it will run most of the way around the track but will occasionally stall out and my controller flashes.  I am noticing lots of sparks that appear to be just inside the wheels around the axle.  I suppose this is a result of the wheels?   I am going to go ahead and order replacements.
On the bright side, Ive discovered how smooth these old Athearns are, even in DC mode.  Either way they are nice trains.   This is a bit of a tangent, but on these Athearn PA1s, some have metal trucks, some have plastic.  Two of mine have metal, one has plastic.  Is there any consensus one which is better, or is it just a matter of personal preference?  The metal ones are a bit heavier, but I think the ones are quieter.  As I look for new ones for my collection I am seeing the same road names in both configurations, and Im trying to decide which I should buy. 
Thanks.

Oh wow, I had no idea the wheels came off the axles.   Ok, I think I have enough info to be dangerous now!    Thanks to everybody for the informative posts.  I've learned a lot from them!

I'm new to the hobby too, but I was given a steam engine that was making a squeak I couldn't locate.  When I held a 9-volt to the wheels it wouldn't do it, which clued me in.  It was the cow catcher rubbing on the rails.  I was able to slide the bottom half of the body back and it stopped doing it.  Mabye that was a fluke but make sure you have a little clearance.

Jeff and Jim - thanks for the latest posts.  Very informative.  I believe I understand everything you're both saying.  In one of my earlier posts I mentioned I was just going to switch the contacts on the top and bottom of the motor - so I got that covered.  Understood also on that metal strap across the top - it would dump the current straight to the motor which is the decoder's job.   I know that decoders need a good consistent current so I was already planning on powering the decoder straight off the trucks.  I've already had one truck completely apart (with the plastic removed and everything) so melting them won't be an issue.  I figure I might use a dremel to scratch up a small area to better accept the solder.  So should I run wires from the left side of both trucks together, then to one of the power inputs on the decoder, and do the same on the right?  That way each input will have 2 sources?

Thanks a lot for the tip on the wheels!   I've spent hours "googling" this stuff and never saw that mentioned.   That's the great thing about these boards - you get answers straight from people who know what they are doing.  So both of those companies make replacements for these Athearns with the proper gear and everything?

Jim - good advice on the bulb - I was already thinking about an alternative.  I will look much better when stationary and not emitting light out the bottom.   Thanks for the specs on the replacement bulb - I wouldn't have had a clue.  I know LEDs are popular too, and I think you just have to put a resistor in series with it?

Again, I really appreciate you guys taking the time to help.

Glad you mentioned the stall amps Jim.  Again, being a newbie I assumed they were a bit overbuilt and would handle any loco.  Mine is the gold, flat-sided motor, so hopefully 1 amp will be enough.   I got one for $17  including shipping, so I won't have a lot at stake, which is good because I don't have a way to measure the stall amperage.   I guess if I hold the loco back and hit the throttle, and the decoder starts to sizzle and smoke, it's drawing more than 1 amp.   

I'm learning as I go, and these posts have been really helpful. 

Cool!  This stuff looks fun.  I'm total computer nerd (IT analyst) and this DCC stuff is a great way to combine my love of trains with my love of 1s and 0s. 

Thanks everybody for the info! 

BTW, I found that just switching the lower and upper copper strips on the motor works great.  that way I get a perfectly smooth one on the bottom what I can easily isolate, and the metal prongs on the top should easy to solder wires to.

Awwww, I see.  Ok, that makes sense.  Yep - you're exactly right - I see those 2 prongs and the look like they would eat through tape in time.  I will Dremel them away.

I know the EZ command can't progam the CVs, what I meant is if I bought a programmer, would it be able to program the Bachmann decoder I mentioned.

Thanks a lot for the help!   

My Athearns is the older style (pre '89 I think) PA-1.  It doesn't have any springs....or wires for that matter.  It's a very simple design, so I figured it would be a good candidate for my first decoder install.  Yep - I understand that a decoder is supposed to isolate the motor from the power, and since the Athearn PA-1 get's power through the trucks and into the frame, I will have to make sure to isolate it.   Thanks for the reply.

Thanks for the quick response! I'm new to the hobby, but I am pretty good with a soldering iron and know some electronics basics.  The trick with the Athearns is the frame is part of the circuit so you have to isolate the motor from the frame if you install an encoder.  Should be an easy install.

One more question about the Bachmann decoder, if I get more involved in the hobby (which is looking likely as it has been a great stress reliever!), and if I buy an NMRA compliant programmer, will I be able to change the CVs on this decoder?  At some point I'd like to run my Athearns in consist with my Bachmanns, but I have a feeling that at the same speed step they will be running at different speeds.  I'm guessing you shouldn't put trains in consist if they are not matched as far as speed.   If I can change the various CVs with a programmer I would be able to get the speeds to match a little better, right?

Thanks!