I had a non start Poulan Pro blower (2 stroke) that indeed had the ring carboned up.
Once cleaned, it starts / runs fine:
Recently, I had a weed eater that didn't want to start. I set the engine at TDC and put
Seafoam in the cylinder and let sit for a day. It cranked up first pull the next day and still runs fine...
If you can look into the exhaust port and check the piston for any scoring would be helpful. Checking compression, at least 100PSI would also help with diagnosis. A peek down the cylinder with a bore scope/camera would also be helpful if possible...
Pulling the cylinder and cleaning the ring(s) isn't that hard. Just make sure you have gaskets etc. As for torque, good and snug with RED loctite has worked fine for me...
I would check the above first (and Seafoam), before pulling the top end apart. As it is an older engine, a new piston ring couldn't hurt..