transmission pulley not turning

[oggie]

My Craftsman Mid-engine rider, 536270290, runs great and the blade turns fine however, it will not go forward or backwards. With the engine off I can push the mower easily in neutral but not if I put it in any gear. With the engine running and the brake off the drive belt is turning but the drive pulley (PART NUMBER: 1401077) does not turn in any gear not even neutral. I noticed that the idler pulley (PART NUMBER: 1401252) is pulled over so far that it butts up against the frame but the belt feels tight enough to turn the drive pulley if there isn't a great deal of friction from the transmission. My questions are 都hould the drive pulley on top of the tranny turn freely when the tranny is in neutral? What could keep the tranny locked up?
Thanks for all comments and suggestions.
Oggie

 

[Carscw]

Ok the pulley is not turning but is the belt turning?
Can you turn the pulley by hand with the belt off?

(( racing is the only sport that you need two balls ))

 

[oggie]

Yes, the belt is turning. No I cannot turn the pulley by hand.