Cub Model 1320, No reverse on hydro

[mmfarish]

Bought this tractor last week as is. Excellent shape except it WILL NOT go in reverse. Runs in forward just fine and goes into neutral. I have adjusted the fwd/rev lever every way you could adjust it but still , no reverse! The dump valve operates good. Can anyone give me some ideas of the areas I should check to correct this? How about the check valve balls and springs?
Thanks for any replies! /forums/images/graemlins/confused.gif