Here's one I know Bill tgo can handle....
Every solstice, I oil fingerboards and change strings. (I know, sounds like some weird pagan ritual :-), but, as a teacher, I'm always off during solstices.)
When it came to restringing my baritone twelve-string, which came equipped with Schaller locking machine heads, I was stumped.
Unscrewing the knurled knobs released the old strings, but the holes where I want to insert the new strings are blocked by what I'm guessing is the set-screw or locking screw.
How do I open the hole to insert the new string? I'm reluctant to use hammer and pliers until I know what I'm doing :-).
TIA.