I just scoured the FSM.  The only check valves I could find were in the engine and in the 3d SCV.  The parts manual also doesn't have any listed.  I don't have a 3d SCV, so I don't think that's the issue.  Thanks for the idea.  I'm going to be checking the filters and screens.  Anyone know if there are kits available to rebuild hydraulic control valves (specifically a rockshaft control valve on a Deere 3720)?
Thanks,
Ed
	
		
			
		
		
	
				
			Thanks,
Ed