The miter gear that runs on the lead screw was original cast with a square key in it's bore. This key has been variously reported as either worn off or sheared off. One of the ways that have been proposed or tried was to bore out the remnants of the old key, drill a row of holes, and insert a row of pins. The downside of doing it this way is twofold. First, until the pins wear s little bit, the surface area of the pins actually in contact with the side of the lead screw groove is only a line. So you would expect rapid initial wear. Second, the protrusion of the pins into the bore of the gear is rather critical. As much of the pin as possible should be in the groove. But it is critical that the pin not touch the bottom of the groove.So I couldn't recommend this method.