John Knopf made a very good replacement peg.  It is great to hear the sweet voice of the John Maxwell dulcimer.   Jim

Jim:   There's your luthier who knows Maxwell dulcimers and could fashion a new peg for you!!

Jim, I have an old John Maxwell dulcimer that was missing a peg when I bought it. I fashioned a new one of maple that looked similar to the original.  His pegs were distinctive.

Exactly what Dan said.  The luthier would have to have your instrument in hand to make a replica peg; it's not something that can be done from a distance.

updated by @ken-hulme: 07/12/22 07:13:53AM

No there is no off the shelf peg for your dulcimer. Each maker had his own way of making pegs and the pegs were "fitted" to it's own hole. If you can find a local luthier learned in historical dulcimer making, they can "make" you a peg and "fit" it.

I have obtained a John Maxwell dulcimer (1975) three string, which is missing a tuner peg - friction, wooden, with a very large finger hold.  The exterior hole diameter is 11.2 mm, interior size of same hole is 10.34 mm - exterior diameter of hole on the opposite side of the head is 7.6 mm.  Do not seem to be able to find anything resembling the original tuning pegs.  Open to suggestions.  Jim