This is driving me nuts.
What gets me is that it runs great in my hand. I can make it change directions at will and it doesn't miss a beat while I'm holding it but the when I put it on the track, it goes haywire. It may make it to the end of the track and try to switch directions or it may just go a few inches and stop.
I've tried using different pieces of track and it didn't seem to make any difference.