1st pic. This is what the arm looks like after you cut out the center.
2nd pic. The center in the hole saw.
3rd pic. Use a hack saw blade and put 2 notches, 90 degrees apart, in the remaining bushing shell.
4th pic. Use a hammer and punch to knock out out the shell.
5th pic. Got too close the arm when cutting.
Didn't touch the arm.
6th pic. The cut out center section.