When adjusting the lever reach on my brakes, I managed to strip the bolt (push rod) and now it won't budge (the allen wrench will not grab)

I looked at the diagram for the lever and it looks like I only need to take the lever off (remove level pin) and replace the push rod, but I have never done this before....and don't know if this will affect the seal on the master cylinder, etc...

Is this an easy fix, or will it require rebleeding the brakes?

Can anyone be of assistance? Thanks