So your nos speakers are supplied with the inserts?
Do they just press in, or are they bonded by some method.
On my original speakers, the water shield is glued (seems like) to the speaker frame, and round circle marks on the shield (clean spots) are evidence of where the retainers used to be.
I think I have a solution for finding replacement screws.
A fastener house in town sells piece meal and for cash, it's just a question of my knowing the head type, length and thread size.
They'll be stainless steel though, so although the heads will be the exact phillips dome head countersink shape, they'll have to go on a buffer to shine up like chrome plated originals.
They won't have the little taper at the tip though.
I'd be happy to pick up a bunch if you can post the particulars of the screw thanks.