A friend of mine had an zetagi BV131 that didn't work properly.

it still doesn't work but the following issues have been fixed: 

  • ceramic capacitor eploded when testing and is replaced now.
  • 3 lose solderings.
  • the variable capaciter was broken but after a bit of soldering and setting a nice even space between the plates its working properly again.

only big issue now is a tiny crack in the tube so that has to be replaced.

If you look closely you can see a little crack in the glass and hopefully thats tha last thing to do to get it running.