mustang 930A weak drive on right side

[BellH]

My tractor has weak drive on the right side it gets worse at some times and nearly disappears at others It seems like it's only weak if I go forward but seems normal in reverse. Could this be a valve problem? On occasion the left steering lever can get stiff in one spot . If I pull harder it gives , this is intermittent as well.

 

[Tazza]

A good test is to swap motors from side to side, see if the issue moves to the other side.
There is a possibility that the issue is a shuttle valve in the motor that is sticking.