I'd hate to shelf these . They have been good to me . Just an older pair of Trinovid Leitz and I'll be damned if the tab didn't shear off and disappear . It may be impossible to repair... so any ideas for a fix ?
Ziptie a small loop of 550 cord just above the broken area. Then use the 550 loop to run the neck strap through.
If the ziptie slips then take it off and add a little rigger's tape underneath to give the ziptie something to cinch on to and put another ziptie on. I'd bet this will hold for quite a while.