If you've tried all of the usual tricks to get them to work and the adjustment
screw doesn't help, I would forget it. Taking these apart will probably just
show you that the internal coil is burnt out. Plus, riveting them back together
will never look right. They were not meant to be rebuilt.
There are firms that do rebuild these, but it's very expensive. Try to find
a good used ones that work (it's possible, they're around) and go from
I had to replace all 3 horns on my '55 Eldo. I took the trumpet apart only
to find all the electrical parts burnt out -- it was toast.
Give Honest John a call, he has a yard full of parts cars and tons of pieces
on the shelf. These aren't that hard to find.