I bought a new scope, Tektronix TDS1002. It's an absolutely lovely instrument! The feelings I can only compare to are what I felt when I bought my first scope: it's a completely new world. Thanks to it, I can now see many problems that I wasn't aware of before. I already fixed some, some are sorted out as not dramatic.
Anyway, the updated schematic of Hetski is in there, just in case. Most significant fix is converting 25MHz distribution into a sort of transmission line, terminated at far end. The need for extra power filtering also has become evident.