older metal Powermaster 66

[BTair]

I recently inherited my grandfathers old metal receiver Powermaster 66. When I first got it, there was no resistance at all when pumping, so I took it apart thinking something was broken inside. Found some videos online, oiled the orings and put it back together. It now has some resistance when pumping, but does not hold air, so I'm guessing the seals are bad. Wanted to see if anyone had any experience working on these, and a good source for parts? 

[Roadworthy]

Mac1 Airguns will probably have parts and advice.  They can even do the work and do it well.

[rangerfredbob]

The parts can be had from Crosman themselves and will be much cheaper than anyone else. You will most likely just need the exhaust valve but a whole valve is around $7 plus $4 shipping. A new valve should drop into your old gun without issue, just make sure the exhaust valve stem sticks out the back the same distance.

The older valves had a brass exhaust valve with a green seal insert, that insert has a tendency to disintegrate after time.

[birdmove]

   That 66 should easily be worth fixing. I have a newer one that is, alas, a plastic one. But, it sure groups well, and the trigger is just fine.