Got a TN65, not had long. Started cutting with disc mower, in heavy grass the pto would bog down then speed back up when I would stop. Could it be a hyd /transmission filter problem?
There is nothing hydraulic about your PTO. It's strictly a mechanical clutch. There should be an inch or so of free play on the lever before it shows resistance as you continue pulling it up. My guess is the cable is out of adjustment, stretched, or something like that. It should take considerable force to pull the lever up. If it has a lot of free play and is easy to pull the it probably has little or no compression on the PTO clutch disc and will likely slip under much load.
Ford 7710, Ford 550, Ford 1910, Ford 4430, KD Forklift, Ford LGT17H, New Holland L255 Skidsteer
It could be that you are cutting too fast or too much grass for the mower. If the clutch was slipping, it would not bog, but would slip. Stopping and letting the mower clear is why the engine is speeding up.
I agree on the clutch though, it is purely a mechanical, dry double clutch setup.