How can a gun barely fire? Do you mean it fires, feels like has insufficient recoil and therefore fails to chamber the next round?
First, make the sure rifle is completely clean and properly lubed.
What kind of ammo are you using? Tula, and other steel cased ammo is known to be unreliable in the M1Carbine.
Even if it isn't steel cased ammo, try another brand of ammo.
Make sure the magazines are clean, and try a different magazine. If you don't have one already, try a USGI magazine or even the newer 15 round, not the 30 round, Korean manufactured magazines should work fine.
If it is not cycling properly, the piston may be binding. Ideally, you want it to slide in and out on its own, but not all of them do. If it is really hard to move, it may have built up carbon. You should be able to soak it and blow it out, and work it until it loosens back up. If the piston is binding, it will rob much of the energy needed to operate the slide.
The rifle design is marginal by nature, so a lot of things can cause it to run crappy. But I would check the basics before paying a gunsmith. I would ask whoever you bought it from if it ever ran correctly. If it did, you should be fine following the basics. Some of those Universals never ran right, even when new. If they can't assure you it ran good at some point in time, you may be wasting your time.