I have a 2011 troy bilt pony riding lawnmower and I just put new drive belts on and now even with the brake pressed the mower still moves in gear. I tightened the brake and it still moves. it also is hard to take out of gear even with the brake all the way depressed. I think the variable speed pulley is bad, but don't know how to check. I put lithium grease on the shaft and the middle pulley moves up and down better, but did not help. Any advice