Originally Posted by
DT Fletcher
Most anything is rebuildable, given enough time, effort, and the right parts. Back in the day, these pump assemblies were never rebuilt for the simple reason that Crosman didn't sell the individual pump cups. That was the basis of my statement. Today, with replacement pump cups, they can. Which, clearly, is (good) news to me. Same with the old 150/160/180 etc model exhaust valves, until Rick started sourcing the proper seals, these valves were considered non-rebuildable, but, today they are. Fortunately, I tended to keep these valves and had a coffee can of 'em which I proceeded to rebuild with parts from Rick.
Like I said on the other forum, I would never rebuild one of these guns with that small check valve seat: it's unreliable and was replaced in production by Crosman with the large version.
Pump adjustment: Per Crosman factory engineering, the pump is properly adjusted when the pump head presses firm against the air chamber and then just enough more so that the pump rod "over-toggles" which forces the pump head against the air chamber and hold the pump arm firmly in place. No other adjustment is (factory) acceptable.
I never worried too much about the air hole. The pump head is not very effective when run in reverse and unless the pump arm is hard to open up, you probably don't have a air supply problem. In other words, don't use the air hole to determine pump arm adjustment.
Didn't see what oil you're using. Most oils and all oils intended for spring guns, are not acceptable. I presume you're using Crosman oil, or MAC-1 Secret Sauce (I know the secret, if you're looking for a local source) or .....?