I thunk I heard that you just push the valve out the bottom, after unscrewing the valve from the tank. Then, replace an o-ring. Last time I needed a big o-ring, about 4 1/2 inch, it was 75 cents at the local chain/bearing/power transmission products store. Tractor supply? Ace hardware?
So far, I've had more experience thinking than I've had brewing....you don't think they are mutually exclusive, do you?
57 batches so far,
33 wine, mostly Loquat, peach, plum, prickly pear
22 beers and ciders
1 Tequila, from a prickly pear wine experiment that didn't work. I call it "Prickly Heat"