crftsman rear tine tiller m#917294482 wheels not engaging. tines engage?

I dont think my Tiller qualifies as a lawn mower but its not any of the things on the list so i put it here. And..Since theres no room for my question in the box where it says to type it..which seems typically hokey along the lines of this entire ordeal that should be simple. ..i will ask it here and probably not get an answer..the tines engage and turn solid..the wheels just stopped engaging after it suddenly jumped around and backed up knocking me on my but and sticking in reverse when the shift lever was still in forward till.. thank god for that guard that i almost removed to get down deeper but didnt. Then it went limp..the tines work and engage and disengage as normal but the whewls are no longer powered forward or reverse..i lifted it and theres no sign of any sort of contact going on with the wheels..they spin freely when pushed but even in gear they are neutral..pushing them with it on blocks and in gear lever down they were free and no sign of contact inside. The gearbox diagram only shows one chain inside..not two like all these solutions claim..so i called sears directly..nothing i called craftsman direct.. and nobody can give me any info one way or the other..so do i tear it apart when no solid info seems to exist on this machine..when even the parts dealers dont know if theres one or two chains inside..or do i buy a mule and strap this chunk of expensive tin to its back and weld a bicycle seat to the handlebars and know i wont have the same problem again? What can you do when nobody knows whos supposed to know? (Theres two ways you could read that last sentence..i meant it both ways!)