I'm diagnosing a 1955 850 for a guy. runs ok but 3 pt hitch doesn't work. I'm familiar with the pump in the belly like my 8N has but have no knowledge of the external pump style this tractor has. I assume there are 2 ports in the trans housing, a feed and a pressurized return when functioning correctly. there is an elbow coming off the top plate under the seat which I put a gauge on. no pressure reading but I'd imagine it is just circulating in an unloaded type condition. I saw where someone suggests moving that top plate to block off those ports on a 600 series. If I do that how and where do I tap in with a gauge. I am also a bit confused about the small lever under seat position. 8N has that also and I've read up on it but that never seems to work correctly and I've gone through that with a fine tooth comb. that's a whole other project so sorry disregard that one. any help is really appreciated