Is it common for a tuner/"machine head" to eventually stop working after a few years? I have this old Squier Strat from 2003, and no matter how much I turn one of the tuners it doesn't move the part that winds up the string.

I don't remember knocking it off anything. Maybe it needs to be oiled?
Not much. It's only a new machine head. To be honest just get all new ones, so they match, plus if that one has been stripped the other ones are likely not far off the same too.
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Squier Precision Bass Special in Antique Burst (LH)
Rotosound Swing 66s, 45-105

On slapping on a bass:
Quote by supersac
pretend its a woman
i have no helpful advice