Teh solenoid just has a lever that pushes the metering valve closed. If it's sticking then you probably just need to replace it. No need to tear the whole pump apart or mess up any adjustments. Just take the wires off it, take the thress screws off that hold the cover on and take the power and ground terminal nuts off and the solenoid will come right out of the top cover. No need to mess with the cold start solenoid on the side of the cover.
If the problem you are having is with the schrader valve can you just put a new core in it and have it work? Or is the leak in one of the lines or somewhere else.