Ifyou don't want to do it yourself, "Wonky Donky" on here will do it. I have used him for both modern and classic repairs and he is very competent, prompt, and reasonable priced and I can highly recomend him. I know he also does the classic repairs for the UK FWB importer.
If you can't find his contact, email and I'll forward his email to you.
Best of luck
Robin
Walther KK500 Alutec expert special - Barnard .223 "wilde" in a Walther KK500 Alutec stock, mmm...tasty!! - Keppeler 6 mmBR with Walther grip and wood! I may be a Walther-phile?