You should be able to identify the front thread size by the drilled hole diameter if you have access to some number sized drill bits. A #31 drill should go in if it's a 6/48 thread, and a #47 drill bit should fit if it's a 3/56 tpi.
The mid barrel bead is probably a tapered press in job. You'll have to pick out the ivory piece; a small drill bit turned by hand in a pin vise might work. Then, using a fine pointed scriber, carefully collapse the edge of the metal portion to pry it out. You can tap in a new one with a nylon punch and some Locktite.
Perhaps try roughing up your pad with some medium sand paper to take the gloss off of it? Might not look real pretty though.
Good luck with your project! Joe
