Compression rings are made of cast iron.
There are brass ones and nylon ones.
Normal piston have 2 compression rings and a 3 piece oil ring. Some aftermarket rings have a 2 piece zero-zap second compression ring to reduce blow-by.
loss of power
2 compression rings and one oil control ( helps scrap excess oil off cylinder walls)
Compression blowby is air, fuel, and exhaust gasses slipping past the piston rings into the crankcase.
You don't repair compression rings you replace them.
If you're getting gasoline in the oil, then you have bad piston rings that are allowing gases into the crankcase. You can find which piston(s) have bad rings by doing a compression test; a cylinder with bad rings will have lower compression.
It is the leakage of compression gasses past the piston rings.
Bad compression rings can allow gasoline to get into the oil.
Bad compression is usually worn out piston rings, no compression is usually bad valves - assuming it's a 4-stroke.
compression rings on pistons are worn out or broken
because somewhere you are "leaking compression" with bad piston rings, intake or exhaust valves or similar.