Thanks for the helpful comments and you have given me a new perspective on the problem.  The board appears to be in tightly and the wires have been checked and are in securely.  I was concerned that the shell, which I know is plastic, though the cab does have metal weights inserted for improved traction, might be pushing the board down and making contact with the metal body.  Coincidence or otherwise, not having kapcan tape, I added a piece of black electrical tape under the front of the board, put the shell on and have been able to get a steady running engine.  Though not nearly good since it runs but at a slower speed than expected when compared with other switcher type diesels.  The tape may have be keeping other things from moving.  Thanks again for your input.

PS - I had no intention of violating any blog protocols and I appreciate Bachmann's comment.

From what I've read the poor design on the brass contacts on Walthers SW1200 switcher and the easy potential for breakage of the contacts when removing the shell to access the motor, is common. I ordered a new walkway with intact contacts from Walthers.  I also installed a Digitrax decoder since the model I had was Dcc ready. The decoder went in fine.  The problem I am having is the failure to get a stable electrical connection again.  When I put the walkway with contacts on the un-shelled  body I get a connection and the engine runs.  However once I connect the walkway to the shell and place on the body, there is nothing.  Remove the shell, connection restored.  Put back the plastic shell and nothing. My feeling is that somehow the shell (with new contacts) is shorting, but how or why since it is mainly plastic.  Can any one offer some help?

What make of turnouts are you using?  I've had this problem with several Atlas turnouts.  The problem is there is a dead spot.  I used a pen type current tester and found on some turnouts current was not flowing in a portion of the turnout.  Depending on the spacing of loco wheels and contacts, certain locos stop at that track connection.  A slight "nudge" got things moving again once wheel contacts hit the rail with current. Check the current in the track where the locos stop.

My appreciation to those who have offered advice.  The problem has been corrected at least to the point of getting power to run my DCC ready loco as far as I have feeders connected.  I do have one of those HF "cheap" multi-meters but once I saw I had power checking track voltage became less important. To Hunt: mistake was my brain not registering what my eyes were seeing.  Once both of them were working together it was an easy fix. 

Yes I am using the AC setting on the meter.  All plugs in proper place. The Cab is reading as per the manual.  I had placed a dcc on board diesel on the segment with feeder wires attached.  Initiated programming as per manual but got no indication of power to track.

Re Hunt comment:  You said my meter would get an inaccurate reading.  I am getting no reading.

Working on installing bus and feeders.  I thought I would fire up the Power Cab, as per directions.  I also hooked the track wires into the power panel.  I had feeder wires  hooked up to one section of track.  However I was unable to detect any voltage.  So I checked voltage at the power panel wire "do-hicky" connector.  Again I was unable to detect any voltage from the track wire connection.  What am I missing regarding voltage? Is it possible the voltage meter will not read low voltages.  It only has 2 ranges, 700 and 200v.   I am using wire connectors from bus to feeders. The cab powered up as it should.  Power to the cab but not to the tracks. I will contact NCE tech support but maybe there is a simple fix or explanation other than it's defective.

Maletrain thanks again.  My bus wires are running parallel (of course) around the layout. Is there any concern if the bus wires touch or do they need to be separated a certain distance.  I am not planning to  twist them as I saw in some videos.

Bigal232 - search YouTube. There are numerous helpful videos.

Thanks to everyone who has offered help.  I spoke with a tech person from NCE.  Really helpful person.  I've decide to remove the old block system, and run a bus line with feeders @ every 3 feet.  I will use 14 awg for the bus and 22 gage for the feeders.  One question I still have is:  a preliminary marking of feeder points from the bus line, show that the spacing can be a little more than exactly 3 feet.  I am assuming that +- a few inches will not be significant.  Also if I reuse existing wires for feeder lines can I get away with 20 gage vs 22 gage? Is it dangerous or does it create a potential problem if feeder wires are a mix of 20 or 22 gage? Thanks again for any additional help.

Thanks for replying again. I have a small n scale layout, 4x6.  simplified it is inner and outer loops connected by turnouts; I have several sidings off of the inner loop.  I have broken this layout into 9 separate blocks, controlled by several Atlas selectors.  I can currently run 2 trains via a 2 cab set up.  My confusion comes from reading the frequently DCC may require for feeder lines.

I recently purchased an NCE Power Cab system.  At this point I am expecting to run 2, possibly a 3rd loco in time.  Since I am new to DCC my first 2 locos will not have sound.

I don't have evenly spaced feeder wires.  I have  assumed the feeder wires to the 9 blocks serve the purpose of adequately distributing power.  From your previous post I understand that I can keep the blocks but may need to change the gage wire from 22 gage to 18 gage.  Hopefully I have helped in giving a better understanding.

Wiring in DCC sounds a lot more complicated than DC.  Do you think using the 6 blocks I have on my small 4x6 layout, I will have a good enough power distribution? Or will more feeder wires be necessary?

Thanks.  What I am still unclear on, is do I need to replace all the wiring from my controller to each block, with a heavier gage wire? I believe I used 22 gage wire.  Should it be replaced with 16or 18 gage wire?  And what does "bus" stand for?

I want to double check what I believe I read in the Forum:  I am switching a DC operation to DCC.  I currently have about 9 blocks.  While blocks are not necessary in a DCC operation, there is no physical reason I need to remove the block controls (plastic rail joiners and wiring).  And it may be advantageous to have blocks if a short occurs?  I am going to also throw in a question about turnouts:  remote control turnouts I have currently will work just fine using a separate AC hookup to one of my DC power packs.  Sorry if this question has been asked and answered.  Thanks.

Thanks much.  The interesting thing I have noticed is that the derailments at turnouts happen more frequently when the diesel is running with the short nose pulling which I am assuming is the usual mode of operation.  Why this happens is a mystery since undercarriage trucks and features look the same on either side.

I assume the gauge tool can be purchased from hobby shops or online dealers?  Are the measurement for wheels also available online?  I appreciate your help.

All switches are remote controlled with switch machines attached.  Derailments occur at different speeds, slow or fast, and without any freight cars attached.