Rotary Cutter JD 5105 tractor with JD MX 6 rotary cutter quits cutting

[jenkinsph]

What if the mower is binding causing the tractor PTO shaft to bind, then causing the tractor PTO driveline clutch to slip? Lots of 3pt implement slip clutches are not maintained properly and they don't work. This would cause the tractors driveline clutch to slip.
Having a known healthy other 3pt implement hooked up to the tractor would eliminate one of the possibilities.

One thing worth considering is the OP stated the mower mows for X feet, then quits. Something could be heating up, then slipping or binding.

Builder,
Anything is possible but I consider what is most likely to be the problem first. If in a few minutes running you can determine which side of the driveline is likely to be the problem you can move towards an identification and solution to the problem. Note TexasJohn said he could turn the mower by hand and that the gearbox wasn't warm. He also said he couldn't observe whether the pto shaft was maintaining speed, so as beenthere mentioned start there first.

 

[hosspuller]

First thing is to make sure the pto clutch is adjusted properly. Likely, it has never been adjusted since it was delivered. The pto clutch wears and if the linkage is not adjusted, it starts to slip. The more slip, the faster the wear, till it slips completely. (like it's doing now) That it starts out running is a good sign. That means it's not completely smoked. Adjust the linkage NOW!