If some one removed the encapsulate and appeared to fix the problem.
Sounds like moisture so has anyone tried baking a transformer, or better
yet place in a vacuum chamber for 24-48 hours then bake at 150 degrees C.
Will not harm the wire or core but might get yet of the leakage.
Years ago I had Baltimore Transformer make some HV transformers for a
project their rig was driven by a gear motor. There problem was the potting
had to stand mil temperatures and 50K feet. Amazing the water collects in a
supposed sealed container going from flight level 1 to flight level 50 and return.
gary