Kevin has the correct idea IMO.
I used to have to deal with o-ring issues, frequently on a system designed to support consistent nitrous flow from the bottle with either CO2 or O2...the o-rings would eventually deteriorate.
Learned a few things...scuba shops and paintball shops are pros. They carry a compound that when applied it makes the rubber swell and often will be a fix if you do not have a replacement o-ring.
A kit like the one attached (note the viton material handles temp swings and harsh liquids like race fuel well) I found to be well worth the money.
Best of luck, Jacob!
Sam
EDIT: PS...I would be more than happy to send any that might work for you.