To test MP pressure you can tee a suitable pressure guage into the line that comes out of the top of the trans bell housing.There's two lines there tee into the one thats closest to the rear.Its the line leading from the auxiliary pump. With the tractor at operating temp and engine running at 2000 rpm the pressure should be 200 -220 psi. High pressure could indicate a plugged oil filter or cooler.Next move the tee and gauge to the other line and recheck the pressure.If the pressure is difference between either line by 40 psi,renew the filter cartridge and check oil cooler and lines.Low pressure in [High MP] range could indicate,improperly adjusted or malfunctioning regulator valve,or malfunctioning pump.Move selector lever to low MP position and recheck. If pressure rises to normal when selector is moved to low MP,check for leakage at MP clutch or clutch passages.If equally low pressure is registered in both MP shift positions the trouble is either in the MP control valve or Aux pump. To isolate the control valve as the cause disconnect the line leading to the oil filter and connect a 2000 psi gauge directly into the line leading from the trans.Start and run tractor ONLY long enough to obtain a pressure reading which should be 500-800 psi.If pressure is as indicated,control valve is at fault.if pressure is low pump is faulty. I've copied this from my book so hope it helps.Larry