No sound from tweeter

I acquired recently a pair of Mission 705 speakers. No sound is emerging from one of the tweeters. I swapped it with the tweeter in the other speaker and it works fine there, suggesting the problem is in the wiring of the speaker. The speakers are bi-wired but the corresponding mid-range is fine, suggesting a crossover problem (assuming one or both of the tweeter wires is not cut at some point inside the speaker). A visual inspection of the crossover does not reveal any obvious problem (over-heating, leaking capacitors etc). The speakers are pretty old so I guess some of the cross-over components may have failed. It's not possible to obtain replacements during the lock-down so short of waiting until I can get the speakers to a specialist I would welcome any suggestions on further diagnostic and/or remedial steps.