I'm in the process of replacing it now, but kind of stuck. I have the feed dog removed, loosened the clamp screw on it and it drops dpwn just fine.. except it hits the edge of the bobbin assy. I need about 2mm of movement to allow it to completely drop out. I've removed the screws that I THINK should allow the needle rocker frame to slide a little but it's not budging. I'm not comfortable forcing anything until I know it needs to be forced. That part is the pivot pin that the rocker goes on.
I put in a call to Bob and will probably hear from him sooner or later.
If I find it's OK to pry that pin out a tad, I'll be golden.