They’re worth fixing. I had the privilege of hearing a pair of modified Hales a few weeks ago, on an advanced system driven by Convergent amps and preamp where there had formerly been an impressive pair of Magicos. The Hales were impressive too!
Grill cloth is available online. You can do it yourself, or have a local speaker repair shop do it if you have one. You could send them out to a speaker replace place too. I’d think places like GR Research, Madisound, or Meniscus could either do it or put you in touch with someone credible.