All of those Walther rimfire rifles use the same basic action, but Walther made incessant changes as they went, and interchangeability apparently was of much less (read that, "no") concern in Ulm compared to Wolfsburg (where the VW Beetle was made). If you break a firing pin, you are in for an odyssey.
I have some parts for them, but not many. Best bet is to send the broken part to Germany for a match-up.
M