I have done that . I cut the stuck of clutch parts of a 6139B. It's often the springs that are broken.  The shaft is one unit from the top to the bottom. The  clutch parts with the finger is pressed on to the shaft. So to be able to repair it you need a special tool to remove that with.  Think i could still have it here somewhere.  I sent a couple of broken ones to a guy. He should see if he could repair them. Haven't seen anything yet.  Can maybe be done but think it's almost impossib