I went look shopping today to check out a couple train stores in the area. At one they had two or three long HO trains running on good-sized oval tracks. One was a steamer (forgot to note the type, but it was big) pulling a long train. What bothered me was the noise. The engine made a fairly loud grinding sound (for lack of a better term); it was obviously motor and/or gear noise. Is this normal? I wouldn't want that on my layout. Is there a way to avoid this? Is it a matter of choosing a quality loco?