Interesting.
I did follow the manual for break-in too.
I will try to get some #8 plugs when I get a chance. It certainly couldn't hurt to try.
However, if the plug is the reason it started acting funny all of the sudden,then it must mean there is damage to the engine right? Because I've never changed a plug in all this time and my engines have run great so far.
The O.S. was still running.....just acting funny. So hopefully the problem is still reversible. The compression still feels normal to me when I turn the prop by hand.