RE: UP4/UP2 plumbing diagram?
Both the UP2 and UP4 have 2 sets of outputs for gear up/down and door open/close. one on the side of the valve, one on the top. Looks like the previous owner plugged off one set of the outputs...for example, You could use one output for main retracts the other for the nose; helps distribute the air a bit more evenly with less restriction.