Walk behind metro 48, pto blogging down

[jbohannon]

after mowing for an hour or so, pto will start to bog down for no reason. will stay that way for a short period of time and then go back to normal. turn it off and engine sounds fine. turn it back on and bogging down again. belt is new. any thoughts?
Thanks

 

[bertsmobile1]

Want to explain that a bit more clearly ?
The PTO can't bog down.
Do the blades turn slowly and the engine labour ?
or the engine just labours ?
What size deck are you running, how high is the grass you are cutting,how much are you trying to cut off are you bagging , mulching or throwing ?