Guys,
I have flipped this engine over, put it under a bright light, and found a mechanical problem. One of the small black cast metal pieces, that holds one of the bars (sorry, if that is not the correct nomenclature) which connects a center wheel to a hollow front piston housing of the engine, is bent slightly inward at the center wheel connection. As a result, this cast metal piece rubs against the other connecting bars when the center wheel rotates around.
When the engine is going straight, the rubbing is small and inconsequential, but going through tight turns, the stress imposed on the drive wheels causes the drive wheel axles to shift slightly inward, which causes this bent metal piece to rub more tightly on the other connecting bars.
I disconnected the bent casting, by unscrewing it from the center wheel. I then taped the loose drive bar up against the side of the locomotive.
The engine now runs throughout almost all of the curves, with only a small amount of slow down. There are still two sections of curves where the slowdown is too much, but I think that this is due to track problems (slight bends or binds), and not engine problems. (I will work out the track problems later.)
My current problems is I can't figure out how to disconnect the connecting bar from the bent metal cast piece, because what looks like the head of a tiny threaded hex bolt turns out to be the head of a bolt that is really just flattened out on the back of the fitting like a rivet. In other words, the bolt is not threaded and I can't unscrew it.
Because this is a mechanical repair issue, on a Lionel, I will open a new thread on the Lionel products board, and post pictures. I am hopeful that someone will be able to tell me how to remove the bad part, what new cast part to order, and how to install the new "bolt/rivet" to hold the drive bar to it.
Thanks for all of your advice.
Mannyrock
