Have a 6010 that has started bouncing or jumping (depending on your terminology) when the car is going up. Runs fine in down direction. Does worse, the more empty the car is. Almost goes away when there is balanced load in it, and does go away after the car gets heavier. Checked tach coupler, brushes, all mechanical components, no issues found. I detest throwing parts at something, we have a tach coming its lead time is a couple of weeks. The comparitor board is pretty pricey also. looking for some guidance from some folks that might have cut their teeth on these things, or more experienced on them.
