Gravely ProMaster 300 Mowing Problem

[Slowjoe]

Need some help ! After cutting for a 1/2 hour or so my machine slows down and loses power but never stalls out or stops cutting. If I disengage the PTO (electric clutch) to the mower the engine RPM's pick back up to the previous operating speed. Sometimes I can engage the PTO and continue cutting with no problem and sometimes the same problem reoccurs. Anyone have a similar experience ? I was told that it could be my electric clutch or a pulley-idler ? However, others say the electric clutch either works or it doesn't. All the belts on the machine and cutting deck are new and have been adjusted according to the owners manual. Thanks for any help or suggetions.

[LLigetfa]

Shut it down when it's hot and try turning the blade by hand to see if it is tightening up from the heat. I'm not familiar with the unit so not sure if a shaft can get wrapped up with fibre and heat up.

[munderhill]

I had a similar problem with a Bolens 850. It turned out to be an idler pully freezing up, bad bearings.

MU