@Tg0dmw
Lets back up just a bit and get more information. First, why can you not service your inflator? I'll attach an Oceanic manual that should be close enough to at least determine if servicing is out of the question. If that turns out to be the case, then proceed.
If you're lucky (don't count on it) the new elbow will screw directly onto the old flange. If not then replacing the assembly is the next step.
Can you remove the entire elbow fitting from the shoulder of the BCD? Or is it bonded to the material? If it is bonded, that will take a bit of work and is doable, but for a used BCD you're putting a lot of effort into it. (Nothing wrong with that, but should be considered.)
If you can remove the entire elbow assembly from the shoulder attachment, measure the hole left in the bladder/fabric. In order to install a standard elbow fitting, the hole should be about 1.10 inches in diameter. A little smaller/larger won't matter, but it should be close.
The parts required are inner flange, butterfly seal, outer flange nut, flange seal, elbow. Plus the corrugated hose and power inflator.
Basically, here is a video of what the replacement entails.