There was another post about this same issue last week from someone else.
Perhaps, you could get together and call the manufacturer of the speaker. A good manufacturer should stock replacement parts even for older models or, at least, an upgrade path to retrofit a newer model tweeter.
Salesman tend to be more interested in selling new gear, so their eyes will glaze over when you present them a challenging problem with time consuming follow up and repair work, all for little profit. A manufacturer has a reputation to worry about and may be much more helpful.