8370 haybine intermittent operation

I recently purchased a case ih 8370. Everything seemed fine last fall. This spring the darn thing runs for 30 seconds then shuts down. Everything turns by hand. I go up to the reservoir unscrew the cap and it runs again. Not being C a hydraulic wizard I'm hoping it's just a filter and maybe a relief valve issue. I know a few on here ran 499 basically the same concept. Looking for a few opinions and options before tearing into hydrostatic pump and motor.

8370 haybine intermittent operation