Tractor Repair: Craftsman riding mower transmission engage, hp kohler, crafstman

Question
Eric,
Thanks for being available as a resource!  My crafstman 19.5 hp kohler hydrostatic turbo cool riding mower will not move when shifted.  I pushed the mower approximately 30 feet back to the garage, but i forgot to disengage the gears using the spring-loaded "thing" on the back of the tractor.  I recently replaced the tires (I've read that this may be one source of the problem.  Is there something I can do to test what might be wrong - I've read tons on this site and know that if it's something wrong inside the transaxle housing, it's most likely cheaper to buy a new tractor than dealing with repair costs.
Thanks  

Answer
Most tractors have rear wheels that are piloted on the transaxle -- double check that the wheels are installed correctly --- if that checks out --- raise the rear of the tractor with it in gear spin the wheels and watch the transaxle input it should spin --