You may have sheared the pin that holds the rim to the axle. Take off any rubber caps you have on the rear rims and have someone put it into gear. Look inside where the axle is and see if it is turning. If it is the bolt is sheared. If the axle is not turning on either side, peek through one of the holes in the back of the machine to see if the rubber disc is turning. If it is then the planetary gear has gone out in the transmission case. If the rubber wheel isn't turning, look for worn rubber disc or a snag in the cable from the clutch preventing it to fully engage.
Scott Deaver: B&S Authorized Master Service Technician, June 2005
