Re: Glazier ir artisan?
Leaded glass would be in the realm of a person who builds/restores suchlike, not a glazier. I doubt that any glass shop is going to take it on. They may have a lead for you. These are always repaired on the flat; IOW removed and brought to the workbench.
Stained glass re-leading is not very difficult or expensive material-wise, so I think it could be an ideal DIY. There are even video tutorials on youtube for the tasks involved.
Remove not the ancient landmark, which your fathers have set.