Hi!I should have asked, how much vinegar would you use for a 10 gallon keg? Or would some warm water and a "slug" of vinegar wiped around with a cloth do?
I had trouble with residue when I used Wizz Oxi to remove labels from bottles. I simply sloshed some vinegar around each bottle and poured it into the next - it doesn't take much. I would try a cupful of vinegar shaken around in the sealed keg then inspect the results.