I was gauging the wheels on my Bachmann Consolidation when I noticed that the two screws holding the flat plate on the belly of the Consolidation which seems to put pressure on the drivers were loose. I am not sufficiently skilled to operate on these engines but when I tightened the screws I observed that just a slight tweeking of the screws resulted in a significant difference in the engine's performance. Turns out, that when fully tightened, the engine wobbles considerably, so much so that the forward driver lifts off the rails and derails the engine on one of my curves. I subsequently spent 45 minutes adjusting the tension on these screws until the wobble went away again and the engine remained on the tracks.
Seems like a flimsy solution, however.
What if the screws vibrate into a new postion and the performance of the engine declines?
Can anyone offer a more secure solution?
I don't remember if all the axels are geared (if I was home I would check). If they are, and if the retaining plate was loose, maybe a driver or two slipped a gear position. If all four axels are not aligned in their gearing it seems this might be part of your dificulty. You may want to take the plate off and look carefully at the drivers and gearing to see if one or more of the drivers need slipped a gear tooth position or two get back in alignment.
Charles
This is another problem common to more than one brand of N scale steam locomotives. The screws on the retainer plate can not be too tight or the runnability will suffer.
This shows up in the SPECTRUM 2-8-0 and 4-8-2. You need only loosen them less than one-half turn. I have yet to have a problem with any screws' working itself loose.
Check your locomotive frame and make sure one of the slots that the drivers sit in are not to loose. I had that problem. Made the engine wobble and derail.