Of course they "sell"  the part,  but the big red sold out button is why I'm looking for alternative options.

I asked Bachmann customer service what material the belt drives for the Spectrum steam were made from, but they sent me here for info.

I have a 2-8-0 which ran great years ago, but has been stored for a long time. I disassembled it for a good cleaning and re-lubing before putting it into service. Also had a to fix a cracked gear on the motor shaft.  The belt drive is no longer round. It's ovalized, probably because it sat stored in the same position for so long. The engine pulses at about the same rate as a belt rotation so I think the belt, by taking an oval shape, is causing the locomotive to surge instead of running smoothly. Seeing that the only way to buy a belt is with a $42 motor/chassis combo, I was wondering if anyone has a special treatment for the belt.

My thought that if it's rubber, than the polymers that keep it supply have evaporated through time and using a treatment like 303 protectant, UV Tech, or even ArmorAll would make the belt more supple and the loco run smoother. Since I'll be out $42 if I do nothing or it doesn't work, I'll probably try it in a couple weeks after I finish a couple other projects.