I had two sets of N gauge trains back in the early 1970s when I was a child. My dad made a Scenic and Relaxed layout for me, without all the sidings and switches. I had this one: and I had this one I was fortunate enough to find both sets NIB recently on ebay. Well, the Aurora set was in the shrink wrap and the AHM set was unused but no wrap. It was the strangest thing, I just started thinking about them and looked them up on ebay. Found them both immediately and both auctions were just about to end, the Aurora set only had about 5 minutes left. So I snapped them both up. Anyway, The AHM loco runs as badly as I expected. It never worked good when I was a kid either. It will go around the track but it's weak and stops once in a while. The Aurora F7 actually runs like a champ. I remember that from when I was a kid as well, the F7 was a workhorse and never gave me any trouble. Since the F7 runs so nice, I bought five more of them off ebay, with the Penn Central shells. I took all of them apart and carefully cleaned them. The Santa Fe F7 came right out of the factory sealed box, and was pristine and ran great both before and after cleaning. The batch of Penn Centrals were not factory sealed and they ran badly both before and after cleaning. They had a lot of oxidation on the brass parts of the motors, like they had been stored in a basement. When I use the Penn Centrals, the motors seem to spark a little and they surge in speed, the speed increases and decreases. Is there a trick to making these run good? Any suggestions? Any Aurora F7 gurus out there? I wouldn't mind getting the AHM loco to run better as well. Thanks in advance for any help.