Hi Ralph,
Remember how well Mark Radcliff's engines ran at the Chicago contest? He disassembled them, installed new bearings and reassembled them. I assume he used new gaskets, o-rings, etc, too. It's an easy way to make an oldie a like-new engine and any air leaks will drive one crazy.
If I were to assume what your problem was in May, rebuilding the tank, using all new fuel lines and cork, etc, and a bearing and gasket overhaul on the engine I bet would do the trick. I remember you deadsticking your landings too, an unreliable idle is a sure air leak problem.
Hope it's as easy as that, that's a cool looking Saturn in flight. That OPS was a screamer, but it was so scary when you'd go vertical with that surging, you're a brave man!
Hope you and your family is well and we'll see you next May!

Chris...