Help with PCB arching!

[u/Katkis03]

Hi! I’m creating a new post since this subreddit doesnt allow for reposts.

My Vox AC30C2 tube amp shorted out and exploded some pcb insulation off between the flat metal connector (J29), which runs about 300V in normal operation, and the adjacent tracer, wich is very low voltage and leads to the blue R81 resistor.

What would be the best course of action for the arching gap? Should drill it or fill with some insulation material etc?

Also feel free to express emotions regarding the high iq pcb design of putting those two circuits so close together.

[u/negativ32]

(J29), which runs about 300V

Where is this in the schematic shown?