Help dresser 530 trans issue

I have a dresser 530. It's just now started to not want to move forward or reverse .the top driveshaft I assume is the input for trans is not turning just creeps and you can stop it with your hand I cleaned both suction screens and changed filter in the can. Still same problem. You can fool with it and finally get it to go and when it starts moving as long as you are using it it's fine but if you stop for any amount of time it won't move again. I checked all hoses for sucking air all look...

Help dresser 530 trans issue

Help dresser 530 trans issue