The pto in our 75C is slipping.  When engaged, it might work for a while, and then it loses its torque----------kind of like oil is bypassing, or "belts are slipping".

Ziegler Cat in Des Moines says that such is highly unusual, and they really have no experiences to draw upon to tell us how to check for the probable cause.

They say to check the oil pressure first, to make sure the clutches are engaging.

So...........

1.  Where is the nipple on that pto unit to which we can attach a pressure gauge?  Zieglers don't know, and the service manual is not clear.  

2.   Any of you had this problem..........likely clutches, or just hydraulic pressure? Appears to be real job pulling the unit.......so we would like to have a feel for the problem before actually yanking bolts.  And, if it appears to be a major problem, the machine will go to Cat.........but I hate to truck that tractor up there and spend 500.00 to find out it is an o ring.

Thanks.