A patch job may prove difficult to gear, I have done this to vintage toys w/little success, usually gear breaks again where glued from stress. A good amount of torque is probaly needed for large old type tuner to "clunk" into place. Adding metal reinforcements on both sides as patch would work if tolerances for entire assemly allow for extra room. What about Thin washers same diameter as gear, drilled w/ holes (to fasten both washers and gear together) at three corners in triangler pattern??
