Pto problem

[Edwardo]

MX 5400 Hydro. I was bush hogging the other day and the Pto quit working. I can press in and turn the knob and the Pto engages but when I let go of the knob the Pto shuts down. I try it over and over but same result. The Pto runs as long as I hold the knob in the on position. What could be the problem?

 

[whatsupdoc]

Try pressing down, turning and holding for a moment then release.
Sometimes if I do it to fast the switch will not hold in the run position.