Check the driver quartering.   One of the wheels is probably far enough out of quarter that you can see it.  When the crankpins on one side are at the top of their travel, the other side should line up horizontally.  You will have to completely dis-assemble the model to fix it, but you can probably twist the wheel into place by hand.  I just did it 2 weeks ago to a 10-wheeler, without a quartering jig.  Disconnect the piston rods completely, leaving just the rods connecting the drivers, and roll the mechanism by hand.  When you feel the bind, you should see which wheel is out of quarter.  If it can be turned by hand, just move it a little at a time until the bind is gone.
If it won't turn by hand you will need a wheel puller and quartering jig.  Northwest Short Line makes them.

Mine run great, although they are a little light.  They pull 6 or 7 freight cars on my layout, but that is all I want them to do.
Neither the blue, yellow or amber lights are appropriate, but I guess those are the only color options available with LEDs.   I removed the lenses and replaced them with MVProducts lenses.   

Part of a panoramic view of the American Agricultural Chemical Company's phosphate plant at Pierce, Fl, showing Charlotte Harbor & Northern covered hoppers in 1929.

http://www.fpc.dos.state.fl.us/geology/ge2402b.jpg

From the photographic collection of the Florida State Archives.

AAR interchange rules required removal of roofwalks beginning in 1966.  No cars could be built with roofwalks after 1966.  As cars were rebuilt, the roof walks had to be removed, brakewheels lowered and ladders shortened.  As time wore on, shippers wanted newer, larger and more modern cars to load, so 40 foot boxcars, and older 50 foot cars, began to disappear.  Once cars reach the age of 40 years, they can no longer be accepted in interchange.  By the early 1980s, 40 foot cars began to disappear from the rails.  By 2006, all cars with roofwalks had to be retired from interchange service.
AAR rules only apply to member of the AAR, and the member railroads CAN ignore the rules of they want to, but they do so at their own risk.  If a railroad accepts a car in interchange service, when the car has been banned, and the car causes a derailment, the carrier is on their own...the insurance companies have cause to bail out on them.   When a car inspector refuses a car in interchange he does so because his paycheck is at stake.
You may see cars with roofwalks that are in company service, but you wont see very many.

Thanks guys;  I have one of those stacks.  It is much too small...looks like it was made for a tiny shay.  I do have a congdon stack from Keystone Locomotive Works that will work, but I would like to have cabbage stacks.
I have photos of #103 in 1944 when it had a stack that looks like it came off the General.  Bethlehem Car Works makes a Jersey Central tender that would look good behind #170...

This loco was built for the Charlotte Harbor & Northern RR in Florida.  Originally numbered 8.  Note the paint and striping...identical to Bachmann's russia iron boiler...from the Florida State Archives.

http://fpc.dos.state.fl.us/reference/rc13007.jpg

When the CH&N was taken over by the Seaboard the engine's number was changed to 103.  It was then sold to my local logging company in North Fort Myers Florida.  From Don Hensley's TAPLINES website:

http://www.taplines.net/dc/dc103drinkingswampwater.jpg

That engine was used until 1944.

Here's another 4-4-0, #170, scrapped in 1940.  From the Florida State Archives:

http://fpc.dos.state.fl.us/general/n038667.jpg

This is #10, a ten wheeler.  Compare the boiler to Bachmann's...from the Florida State Archives.

http://fpc.dos.state.fl.us/general/n038665.jpg

In this picture # 10 is painted red.

All I need is a source of those stacks...