mm wrote:

==Alternatively, what you use to glue a a broken white plastic (or
nylon?) gear to a metal shaft? The gear is in two pieces, and when I
put half of it in place, and rotate the shaft it's a tight fit between
it and each of the gears it mates with.

No glue will hold well enough for nylon, especially on gears. The
only repair that will work is melting the broken pieces together, such
as with a woodburning iron or soldering iron (nonstick Teflon
woodburning tip is better) and identical nylon as a filler. I've
never fixed big or high-torque gears this way, only tiny ones, such as
those in ancient TV tuners (and I still have one of those TVs but
haven't rotated the tuner in a couple of years).