It's fairly easy to isolate the leaky seal but not that useful since the pressure chamber will need stripping anyway.
Will try to get photos of similar innards in a day or so if it helps.
I should have chipped in earlier, Crosman are very good at using tried and tested components in different guns in order to keep things simple.
The seals of a Crosman 140 rifle are the same as used in a Crosman 1300 pistol.
The exhaust valve from a Crosman AS2250 fits directly into a Sheridan C9 Silverstreak.
Anyway I'm pretty sure Ped could supply the OP with the appropriate seal kit for a Crosman 2200.
All the best Mick
one complexity with the 2200 is they often have a blow off valve fitted underneath the main valve. quite a few extra seals to leak. Just strip it all down, remove the valve, easiest thing to check is the outside seal, see if that's gone. If it's leaking through the valve (stem), you should have air coming out of the barrel as you pump (bolt closed). If it's leaking through the blow off, air will come out of the small hole underneath, just in front of the trigger. But I'd just strip and replace all the seals and stem.
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.
Thanks for the advice Guys, I don't think any air is coming out of the barrel when its pumped. I have limited (OK no) skills regarding this stuff so will probably drop this off for GGGR who is a massive fan of Crosman so I have been told (ahem). Its such a pity that these rifles are almost finished when something goes wrong, having said that I suppose its 30 years old and made of very cheap materials.
Thanks for the pointers Guys, at best this may just be decorating my gun rack.
pretty certain it'll be the valve stem but the relief valve can cause issues
stripping the valve can be a bugger as they were loctited quite often and gripping the front is awkward without collets or a lathe
i generally have one go at just undoing it before resorting to a bit of heat
the original stems in these are prone to degrade just like the 1322/77 stems of the time but can be replaced with the new 2100 stem
It sounds do able ped but maybe just a complete new unit? I dont know if they make them anymore or if anyone imports them-opening that mazak case is a stumbling block. Maybe better to have it in one piece than permanently apart. I dont even think gunshops would have a go at one?
I am starting to look into repairing it, to be fair the pump seal was indeed hard to find, Lawrie om here saved me.