i have replaced a few bad couplers,there was ground up metal in the bellhousing,it looked like powder,maybe if he looks closely,he can see some of this around the bellhousing,that would sorta narrow it down,on another note,i had a customer tell me he needed a new coupler,after i pulled the engine,no problem with the coupler,it spum the rubber in the prop hub,it cost him 50 bucks to get the prop fixed,and even though he got the new coupler for me to install,he still complained about paying me to change it,thats why i said to check the prop first,just trying to save someone from having the same trouble i had.

Well, it was the prop. Swapped with a good prop, and it ran fine. I wll have the other prop re-hubbed, and all will be good. Thanks for all the input!!