Combines N6 Hydraulic Problem

I had a similar problem on our N6. We first thought a seal in one of the solenoids was leaking and allowing oil to bypass. Our problem turned out to be a wire off the main solenoid that supplied oil to all the other solenoids on the valve bank. Our header lift and others systems either did not work or were very slow. I do not know if this will help or not but good luck.

Check spline right at pump. I think you should be able to see shaft turning if it is. I'm unsure if an '81 had the clamp on spline setup and even if it does I've seen wear someone didn't tighten bolts tight enough to clamp on spline thus they go out over time. I kind of think the combine would move a bit for you like you describe if main hydralic pump failed but ussually would no for sure if tried to move any distance. Otherwise if pump is not working at all it could be either of the springs in compensating valve that is fastened to pump or internal spring that angles the swash plate. Not often a complete shut down of hydralics unless pump just isn't turning.