these guns only build pressure after you cock them, so it may not be needing a rebuild. i would clean it up, open the pump arm, drop 5 to 8 drops of non detergent w30 oil on the felt (spongy oring visible there.) work the pump. then put a couple of drops on the cup and shoot it. see if it holds.
Nice 880.Let me know if you need parts.I can save you some $$$$$$$Thanks Ask ANY other seller if they have a transfer port seal.......Try to re-energize the old stuff first.
Ron's seal kit will get you fixed right up. While you're at it, ask about his trigger mod kit.. day and night difference.
I wish mine had a rifled barrel
The early 880's were not rifled....the 881 was the same gun w/rifled barrel.880's after about April,1979 have rifled barrels.My trigger kit may not work in your rifle... You need to have the flat spring under the bolt for my mod to fit.Daisy's wood stock versions use a bolt that runs from butt to tang, and threads into a mounting plate in the receiver.I can provide that plate.......