Does it fire at all? Like one shot and then fails to fire after that?
When it fails to fire, can you hear the hammer drop or is there no engagement of trigger to hammer (uncocked).
Fail to fire can be the bolt not completely locked into battery.
That can be anything from dirt and crud in the locking lugs and ways to the shooter lovingly loading the first round by letting the bolt close slow and easy.
Pull the bolt handle to the rear and release it to load. Let the spring action do it's work to load the round and close and lock the bolt.
Firing pin could be broken. The front 2/3 is long, slender and tapered. A simple coil spring surrounds it. A broken section can stay in there and if it lines up can continue to fire intermitantly.
Being tapered, the broken section won't fall from the front of the bolt face. But it can slide forward and show itself if you lock the bolt back and tip the rifle muzzle down,,rap on the recv'r a bit.
If you see the firing pin tip hanging out the front of the bolt, it's broken.
If the gas system is fouled, that can cause the rifle to fail to cock the hammer after firing a round, but the action/bolt can be cycled far enough to eject the fired rd and chamber a fresh one.
That leaves you with nothing when you go to fire that next rd,,not even a click as the hammer is not cocked.