If it is Colt's satin nickle, be VERY careful with it. It is one of the most delicate firearms finish there is.
Once you go through it, it is toast, no bringing it back.
Just a hint on assembling a Garand bolt. I can't remember how I did it years ago, but had a devil of a time getting it done the other day.
What I did:
Screw a sheetrock screw into the edge of my bench, just shy of flush.
Take a pair of cheap pliers and wrap some blue tape around the jaws...
There is a pull gauge used to tension the extractor. With a micrometer, you can probably make one yourself.
Internal extractors can be a bit of work to get right, but work fine once set up corrctly.
BTW, is it jamming on firing, or just when cycling rounds?
Look up baking soda and superglue.
I have a shotgun that had a horrible gouge from barbed wire. This totally repaired it and you can't even find it now.
Looks just like the I frame I had, plus, it broke the main spring in the exact spot mine broke, and how I found that the K frame spring is different, but what do I know?
Use an impact driver to remove it. There is a socket that is used for driving wing nuts. It will work when nothing else does. I use an 18volt battery Dewalt impact driver, 1/4 inch drive.