Buy a Quart of Marvel Mystery oil, and put the other pint in your gas tank.
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Back in my RX-7 days we'd use this procedure to clean up stuck apex seals (the rotary engine equivalent of piston rings), but we'd use ATF. It worked extremely well, and you'd get rid of all the mosquitos in the neighborhood for a day or so.If this were in MY driveway, I'd warm the engine, pull the spark plug on the low-compression cylinder, and dump 4 oz of GM Top Engine Cleaner into the cylinder. Rotate the crank a time or two by hand, leaving THAT piston at TDC. Put the plug back in, loosely, to keep debris from falling in. Leave it overnight.
Next day, pull the plug, crank the engine with the starter to assure it won't hydro-lock. Put the plug back in, start the engine, warm it up...and repeat the entire procedure.
If the Top Engine Cleaner doesn't solvent-clean the ring groove with those two applications, it's going to have to come apart. But you could try the Seafoam or whatever in the oil 'n' gas.