I sent the jacket to FLIGHTJACKETS.COM. They were able to put a new collar on for me.
The only reason I didn't send it back to GB is because I wanted to make the collar a bit more like the Nowak or Kelso, which GB can't do, due to licensing, so I drew a template using lots of pics from here and this is the result. They did a stellar job and you can't even tell where the old stitching was.
I couldn't be more satisfied.

Last year, I had these new buckles put on to change the straps too.

Chris