I mowed this morning. Driving and I start loosing power for the hydro going forward and reverse. The mower stays running, the belts are still running, and the engine runs perfect too. But the hydro loses power. Then I flip up the seat where the oil is and it's just over flowing. This only happens when I'm mowing or driving around. The oil doesn't seem to go down where it's supposed too. So is there a clogged screen or filter? Help me out so I can resolve this problem. I can mow for about 30 minutes til I run into this problem.

Its a John Deere 185 hydro riding mower.