The caliper listed for @$230 and I wasn't about to toss it .
I decided to try to make the part. Since it was a very small and I only had an idea of what the dimensions might be, I decided to disassemble an old Harbor Freight caliper I had. Well I'll be damned. The HF shim fit perfectly. I now have a fully functional Starrett 797 caliper.
Just a reminder if you need parts for your high dollar electronic caliper, spare parts may only be as far as your local Harbor Freight dealer