With the valve resealed I had to turn attention to the pump plunger.
A reader sent this trick of using snap ring pliers as a spanner.
Nut, leather pump cup and steel washer in the bottom of the cup.
You can see that a bit of the leather cup stuck to the brass…
A new Crosman pump cup will do the job and the height of the cup is similar.
Checking depth as I bore out the rubber cone.
Cutting off the cup.
Fits fine. I need to make another one with a slightly thinner bottom though as tightening down the nut causes the cup to expand a little too much. With the nut just snug it’s fine.
Temporarily reassembled for testing. I sealed the tube to the valve body with teflon plumbers tape. It’s been holding air for days now, which is a good thing. I’m going to use an o-ring and some teflon tape for the final seal.