At York I bought a new (old stock) set of TMCC Century Club PRR Sharknose diesels, both powered. These are beautifully done engines, but when I got them home, I was really disappointed in the sound quality. First one, then the other engine developed a raspy speaker buzz with the engine sounds. I was about to take them apart and see if I could replace the speaker with a Fat Boy, when I discovered that squeezing the shell on either side of the fuel tank stopped the buzz. When I released my grip I could feel the buzz, again right on either side of the tank. Hmm. Maybe I could dampen the buzz. I cut 3/16x4" strips from a Manila folder, pulled the shell slightly away from the frame and slipped the strip between shell and frame, on either side of the fuel tank. Repeated on other side. It worked perfectly. No more buzz!
Bob