Tractor Repair: IH 574 PTO, diesel tractor, control valve

Question
I have a IH 574 Diesel tractor when I engage the PTO and start to mow it will start to slow down and sometimes even stop.  

Answer
 The pto clutch may be worn out or have low pressure or both.  There is a small tee fitting on the left side of the rear end behind the multiple control valve where you can hook up a gauge to check the pressure.  There should be about 250 psi.  If the pressure is low, there could be an internal leak in the pto clutch, or a sticking spool or blown gasket in the multiple control valve.  Also make sure the pto lever is pushing the spool down far enough on top of the multiple control valve.