My Toro mower has a personal pace self-propel feature that does not work. I took off the cover that is covering the belts and it appears the transmission belt is properly seated in both pulleys. I went to the Toro website and found the parts pdf for my model# 20333 (serial# range 310000001 and Up) but there is no exploded view of the transmission. I unscrewed all the torx screws on the bottom (or top?) of the transmission but it won't open. It is sealed like it is one piece but there is clearly a seam. The manufacturer brand information on the transmission is indecipherable. Has anyone worked on this model, do you have any advice?