AJS & Matchless Owners Club

Have a look down the filter tunnel as the other end cap, the one with the hole in it, could still be down there you need to hook that out of at the least make sure it is not canted to one side which will make it difficult to fit everything back or at worst stop the oil flow. I used to think the spring was there for some sort of pressure relief to allow oil flow should the filter get blocked but there is no way these bikes would build up enough pressure to shift such a strong spring especially as it is almost fully compressed once that end cap is screwed home so any short reasonably tough spring will do.