Fix or replace stripped CO2/Argon regulator?

Hey all,
I bought a used welder a few years back. It came with everything to convert to gas, but I've only ever used it for flux core. I'm converting it to gas as I'm starting bodywork on my truck. I got a tank of mixed gas, and went to hook it up today only to find the regulator screw is broken and stripped.

I'm totally new to this and don't want to blow myself up, so I'm asking for your opinions! Can I tap the regulator and put in a slightly larger nice coarse thread screw, or don't touch it and buy a new one? I'm seeing a new one is $130 CAD at Princess Auto (Canadian Harbor Freight) or I could get one off Amazon for $60 CAD but it won't be here until Monday. A free repair would be great.

That should be easy to fix. The pressure setting screw (the broken off bit) is only adding a bit of preload to a spring under the brass "dome" which in turn is pressing against a metal and rubber diaphragm, behind which is the gas. Disassemble it, get the broken part out and replace it with a bolt. Done.

NOTE: Don't mess with oxygen or acetylene regulators! Inert gas (co2/nitrogen/argon) is safe. But get the tiniest bit of contamination on the high pressure side of an o2 regulator and very bad things can happen.

Yup, think "oxidizer" when it comes to O2.

On closer look it appears the steel colored thing with the divot is what would be #18, the spring button in the parts diagram above. So you just need a bolt the right size, preferably with a rounded nose.

In reply to motomoron:

Thank you so much! Yes, I think the silver bit is the spring button. I can push it in with a screwdriver by hand. I'll take it apart tomorrow and tap new threads once I find a bolt.

In reply to Run_Away:

Glad to help!

Keep all oil away from the O2 regulator, inside and out.