I'm a ford guy.. not a MF guy.. and there are plenty of differences inthe two.. but some similarities.
on fords, there is a top cover port you can add a valve to that grabs hyd fluid before the 3pt lift.. IE.. a series valve. if the remote is in use.. it grabs the oil befor ethe lift.. when you let go of the remote, it becomes open center, and oil is once agian available for the 3pt.
Almost sounds like you have a series valve that is dumping oil to the sump before it gets tot he 3pt, and the spool itself is what is hooke dover to supply the 3pt.
That's all conjecture... I'm sure a MF expert will be on soon.
i was just interested in seeing the setup as it bares some similarities to ford setups.. plus i just had to work on some hyds fro a newer MF, that used a blank tap plate onthe hyd cover to run a fel.. it was an -experience- to work on.. etc.