That's the Sterling Superior. I like those so well that a few years ago when those were discontinued I looked unsuccessfully for a couple of years for someone to make that case in leather. I thought it would be pretty simple but I couldn't find anyone willing to do it. Every now and then I see one on Ebay. Sometimes someone will find one on a shelf in a store room that's being cleaned or something like that, so they put it on Ebay, but you always have to make sure the actually have it in stock.
You might check with a tailor or a furrior to see about zipper replacement.
I think those are great cases, I love the ones I have. Best of luck in your search.