buzzing

It is a relatively new Athearn Ac4400 and it keeps making an annoying buzzing sound. The model runs perfectly fine at low speeds but usually when it make it faster it speeds up normally without any buzz then suddenly slows down and starts buzzing. Every once in a while I can make it run at a...

Howdy, I have a new PS2 engine that has been running great. It's our Christmas engine and it's got about 100 hours on it so far this season. In the last 2 days I've started hearing a buzzing sound. I originally thought it was coming from the track but now I think it is the engine. The sound is...