MIMF

I have used set of Gotoh tuners for a classical. One of the pegs grinds a bit. Having disassembled it and played with it a bit, as far as I can see the root cause is that the cogwheel is quite worn. All the wheels are worn but one in particular seems to be the issue. Are replacements available? Any thoughts where I might get some, especially in Europe.

I have never seen a commercial source for tuner parts. When broke...replace the whole set.

But, it is a good idea to keep any old tuners that you remove because then you will have useful parts for future repairs.

http://www.mimf.com/phpbb/viewtopic.php?f=3&t=4504

There is a discussion in acoustic guitars about Gotoh tuners. The information might help get parts, but I would go with Barry's suggestion.