There is a key pin that secures the arbor from moving that is located in the hammer channel where the curved portion of the hammer goes in the back of the frame. It is sometimes difficult to see because it is usually ground flush with the curved surface of the recoil shield/frame's hammer channel. This pin secures your arbor from moving. One way to remove it is to drill a small hole in this pin, thread it, insert a long but small diameter screw into it and using a automotive dent puller or something similar, apply rearward force to remove the pin. Then you should be able to rotate the arbor out.
This below quote is from one of the below links....
"Getting the pin out can be a major undertaking...that key pin removal can be a pain. If you do this, may think about using a small diameter allen head set screw as your new locking pin...if it ever comes up again, will be glad you did."
Here's another below quote from one of the below links.....
"Before you try any of the suggestions, how about you tighten the arbor, check to see if it is perpendicular to the frame, tap home the dowel pin, and see if that cures it. The dowel could have become loose, but still no wear or stretching of the threads, simply allows a couple thou turn of the arbor. Seat it, if that cures the problem, use a flat bottom drift to upset just enough metal to hold it secure."
Here's a couple of links for you to read that you may find helpful....
http://www.thehighroad.org/archive/i...1846.html&
http://webcache.googleusercontent.co...www.google.com
Hope this helps you.
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