Unless I read this wrong, you do not blindly open up an engine for a piston ring inspection. Once opened this means an overhaul whether you want it or not.
Check the PCV valve first and if that’s ok then go with texases’s advice about a compression test.
Run the dry test first and follow that up with a wet version of the same test.
A wet test simply means repeating the process one cylinder at a time after giving the cylinder being tested a small squirt of motor oil.
If the pressures go up considerably the rings are shot.