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 am having a connectivity issue with my Bachmann Light Mountain in that it often, but not always, stalls at certain spots along the track. Two of these locations are on a turnout, the other is on a straight stretch of solid track with no seams.

Lacking a meter, I simply, slowly, and carefully dragged the wires of an incandescent bulb along the rails at the trouble spots. The bulb never flickered indicating that the track has power throughout.

Meanwhile, the Bachmann Consolidation runs through these areas without a problem.

If, say, the drivers of the longer Light Mountain were, for some reason, lifting off the track at these locations, wouldn't the tender, which has pickup, prevent the engine from losing connection with the track?

Should I suspect the engine instead of the track?