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Jamming tuners

   One of the recurrent problems with old tuners in old mandolins, is that a set of tuners that appears to work fine, jams once strings are attached and they are put under string tension. If the tuners do in fact operate well, off the instrument, then the probable cause is that the holes for the barrels in the head are too large. What often appear to be original tuners, are in fact often replacements, and because the size of tuners was not at first standardised, the holes are often enlarged to fit a different set of tuners with a slightly different barrel spacing.

This is the easy way to fit them..... unfortunately it also leads to problems, as the wood is not close enough to the barrel to support it under string pressure. Typical problems are the tuner jamming; the buttons breaking because of the extra pressure needed to turn them; or the thread being stripped from the worm or cog, rendering the tuner useless again. If the holes are not a snug fit, the best solutions is to fill and re-drill them, though this may also involve re-veneering the head afterwards.

It is also possible to fit ferrules to reduce the size of the holes, but unfortunately this presupposes that the enlarged holes are all enlarged symmetrically.... which is rarely the case.

misaligned enlarged holes during filling 'out of true' visible after careful re-drilling modern ferrules which still need well aligned holes
The section dealing with the process of filling and re-drilling a head, can be found in the Hospital Section under 'Heads'.... here.

Tuners Anatomy

Tuner Repair Tuner Cleaning