I have a steel-string parlour guitar in for some work. It has a slotted headstock, so it has classical-style, plate-mounted machines. Whilst I have been working on it, one of the machine heads has fallen apart. I'll try to explain more fully: The worm drive bearings are mounted on the plate by means of 'tongues' or pins which fit into holes in the plate; on this machine head, the pins have pulled out of their holes. I have put it back together a few times, but it doesn't hold long, once the string is up to tension. Can anyone suggest a way to get it to hold together?
I have tried a spot of cyanoacrylate (superglue), solder, anything to give that bit more grip, but to no avail. I have even tried drilling a little way into the pins with a 1mm bit and hammering in panel pins, to try and spread them in their holes.
The neatest solution would obviously be a complete new set of machines, but this would mean convincing the guitar's owner to spend his money on them - and convincing him that it is not my fault (which I genuinely believe) but either a weakness in the design or the result of earlier damage or wear.
Any suggestions would be much appreciated.
I have sorted it with 70/30 solder and a fine blowtorch. Part of the problem with soldering before was that I was using a standard electric soldering iron and, once the worm posts were in place on the plate, the iron was not nearly powerful enough to heat that much metal - and standard electrical solder would probably not have been strong enough anyway. The solder did spread a bit further than I would have liked, and the heat has tarnished the gilding a bit, so it doesn't look that neat, but it has done the job nicely.