Good luck restoring the Johnson! I had a Viking II when I earned my general license in the 80s, and it was a beautiful transmitter for many years! May you have many happy hours with it!
Is the rectifier tube a mercury vapor type? Or is it not old enough for that type of tube? Mercury vapor tubes will arc. If left too long, unused they need a warm up before plate voltage is applied. Also if stored standing not upright the mercury will flow places it might cause an arc. 73 de VK2AOE.
No, it's a 5u4 duel rectifier. Have several hrs on rig and 2 qso's with no problems.,though a gnd wave contact reported a chirp. Thanks for the comment and 73