I have an older Lifelike British Columbia Railways 720 loco that spins on my Lifelike Power-Loc track. I have thoroughly cleaned all 4 drive wheels but it spins going up the slightest incline or with just a few cars behind it. It almost seems like the lip on the wheels is too high to allow the engine to fully weigh down on the track. Is this possible? I also have a Bachmann 9162 CN loco which is a poor performer, and an RSO Atest 6602 CP Rail loco (uncommon make?) that runs and pulls excellent.