Gas rings and extractor O rings are two different subjects.
To test gas rings, push the bolt all the way into the carrier, then aim the bolt face straight down. If the bolt moves downward to the unlocked position, the gas rings are toasted.
Extractor spring tension, if the spent case is not dropped from the bolt face as the bolt goes to pull the spent case out of the chamber and the bolt begins to reach it more reward position, then the extractor and tension are correct. If the extractor slips off the the spent rim case when the bolt is pulling the spent case out of the chamber/on the way back, you have other problems (weak extractor spring, worm claw on the extractor, chamber fouled or rough, barrel gas port too large and you have over function, or even a worn out hammer or recoil spring), but adding tension to the extractor spring will help band-aid the problem.
And regarding the B/C in the upper, with the upper shotgunned opened and the muzzle pointed downward , the B/C should free run from being pulled all the way back against the charging handle, down to locking up the bolt when you release the B/C.