While running my Atlas GP-35 around my layout I noticed that is slows down significantly, to almost a crawl sometimes, going around the curves ( radius = 10 in. ), even when not pulling any cars. It runs fine on straight track. None of my other engines have this problem so I don't think it would be a problem with the track. I checked the wheels to make sure they were correctly gauged, but other then that I don't have a clue where to look. Anyone else ever have this problem? Ideas where to look or what to fix?