I'm no engine expert, but speedracerntrixie makes a great observation. You won't feel much resistance with that kind of ring until the engine has compression. Even then, if turned over slowly, it may not seem like much. But with a sharp flip, it will feel much greater. It should give a nice "pop" feel even without fuel or the glow plug lit. The compression forces the ring out to the walls, making the seal much tighter. A faster flip overcomes any small leakage it might have.
Scratches on the piston body itself, while signs of wear/maybe abuse, have no impact on the above. Scratches on the ring, or just wear, will allow too much air to leak past, and then even a sharp flip won't provide enough compression. If such is the case, even if the sleeve looks good, I'd likely replace both it and the ring. But with that much wear or abuse, then the connecting rod bearings become suspect too....
And low compression might be the head seal or the glow plug seal, and not the ring/sleeve....or3 maybe all of them!