I have a 1993 Ariens ST1032. It has 2 speeds in reverse. When I put it in the first reverse position (the slower of the two reverse speeds) it keeps popping out of gear and shifts to the faster reverse speed. No problem with the forward speeds. I only use forward 1st and second, the speed selector stays in position. I took the spring off that holds the speed selector and it is not damaged but when I reassemble it it seems like the spring is in the way. Any help would be greatly appreciated.