Revelation BB Gun seals

Hi,

I have an old BB/pellet gun that I am trying to restore back to working condition. It doesn't hold air as it's getting pumped, so I am looking for seals to fix this. The brand it called Revelation and it looks like it's made by crosman. From what I gathered it looks like it was made in 1977. I have found manuals and checked the crosman website but the o-rings they offer are not for this model. I'll try to attach a photo but does anyone have advice of a rebuild kit or replacement seals? Any help would be appreciated
1EF54B4A-19E6-4AAB-8317-86020E4B3E97.1601464959.jpeg

 
The Revelation 760 Powermasters were built by Crosman and marketed by Western Auto Stores when I was a kid. I now own two of them. So they are exactly the same as the regular 760's internally. Just find the date code on the barrel band end cap on models built before July 75. and at the beginning of the serial number on the receiver on post-July 75 models. The Western Auto model number means nothing in this instance.

760revelation16.1601493348.JPG


760revelation17.1601493422.JPG


760revelationb.1601493510.JPG


760revelationk.1601493613.JPG


This last one looked to me like 6/74? Anyway, these pics illustrate where to find the date codes at any rate.