I have had a king keg top tap for about 5 years and worked OK but never used it for the last 2 years. I resurected it and fitted a new tap (dalex) and put my beer in but kept leaking and I used a whole CO2 cylinder just to get the beer out. Couldn't find any leaks so decided on drastic action
I bought a new valve for the top and refitted my original king keg drum tap*, don't like it but it works. I made a porter and put it in the barrel before Christmas, had a few over the holidays and topped up with a blast of CO2. There is about 5 litres left of 23 and every few days or so I am taking a few halves out and pressure still maintaining.
I was very careful fitting the tap with vaseline on threads and on teh top cap and with the new valve seems to have done the trick. For a few quid it saves a lot of bottling
*The drum taps are difficult to turn both on and off but solved this by getting a bit of wood about 3 inches long by 1 inch deep, cut a notch to fit across the top of the drum tap creating a handle and can now operate the tap succesfully with no drips.