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The problem is not likely to be the pump. There is a series of valves inside the lift cylinder housing (where the lever is attached and the oil is added). The most likely culprit is some dirt has caused one of these valves to stick. To complicate things, you have the dual Touch-O-Matic on your MT, and I have the single version on my 'M'. There is an excellent description on the operation of the lift system in the 'M' service manual. I'd highly recommend that you consult the manual before you try and disassemble any of the hydraulic system. I'll give you a brief summary of how the positional control works, though. This is from my 'M', so yours may be slightly different. In the lift mode, the lift lever moves a notched shaft that operates the valve that admits oil to the lift cylinder. The oil pushes on the piston and that pushes on the rockshaft, causing it to move. There is a feedback rod attached to the rockshaft that moves that notched shaft back to the notch point. The notch allows the lift control valve to stop the oil flow to the piston. In the lowering mode, the notched shaft opens a valve that allows oil to flow out of the cylinder back to the sump until the feedback rod again stops the flow by moving the notched shaft. In all probability you have some dirt keeping the lift valve from opening. In this case, you'll have the symptom where the lever moves OK, but nothing happens. The 'M' has no form of oil filter, so any dirt the gets into the system can cause a problem. I have this problem on a regular basis with my 'M'. It had gotten water into the hydraulic system at some point, and no matter how much cleaning I've done, there is always new rust scale getting into the valving and sticking things up. I wind up having to dismantle the system on a yearly basis and clean things out. As far as checking the pump pressure, there's several pipe plugs on the lift cylinder housing, and one of these will get you input pressure. I forget which one, though, and some of the others contain spring-loaded bypass valves and such. Again, you'll need the service manual to be sure what you are doing is correct.
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