Crossman 760 .177 not functioning

[orangeRcode]

I've had this air rifle for over 20 years. It has performed flawlesses over the years. Shot it a few months ago. My son and I shot it 200 rounds about 3 months ago and put it up in the garage as we normally do. Today when I pulled it out it won't pump up. It appears the piston is not holding the compression. I've oiled it but doesn't seem to make a difference. Is there a rebuild kit for it or has it seen better days?

 

[HiredHand]

Maybe this will help.

 

[orangeRcode]

Perfect. I should always start with youtube.
Thanks for the link!