Originally Posted by specialized
I'm goign to guess based on my experience that your oring is shot. If you have squarish orings they should be replaced. When they were new they were round. Years of compression have changed their form to be squared off. Here are some part numbers I dug up from another thread.
Not necessarily true - Most of my kegs came with what are called "Quad O-rings" - which are square in profile.
I replace them with round ones when they need it, but square doesn't mean they are bad.
Look for cracks or strange deformation. If they are still pliable and smooth, there's nothing wrong with them. (Assuming they are the right size in the first place, and don't smell like root beer!)