Sounds like p/n #4 extractor spring, the tip of #5 safety catch plunger, or the detent in #10 safety catch is either worn out or the channel the extractor spring rides in is gummed/trashed up badly.
I think #10 has to be fit, the other two are drop in parts, but I might be wrong about 10.
http://waltherppks.com/wp-content/up...pk-exposed.gif