Found this thread right now ! I’m also looking for a M3x03.mm Tap 
Did someone manage to find one ?

Did someone manage to find one ?
the 3x0.0.25 is also too small so I believe the 3x0.3 is the correct
Yes but where to find that tap ?3x0.3 is 100% correct tap for gen 703 tube.
Yes but where to find that tap ?
Well to be exact it’s M3.05 x .33x0.3 is 100% correct tap for gen 703 tube.