Make sure that the track with the burn spot in it is not broken, check it for continuity. Clean up and resolder all the joints that look poor.
It's pretty unusual to have arcing in the centre of a track unless it's broken. The only time I have seen this is when there are high voltage tracks on both sides of the board and the epoxy on the board itself is breaking down. Make sure there is not a component on the other side of the board burning through.
If the problem is high voltage tracks on both sides burning through towards each other, then cut the tracks on both sides and solder wires across them instead, just make sure both tracks are isolated from each other. If it is a broken track, a good scrape back to bare copper on the track either side of the break and a solder bridge across the break will suffice. If it is a component, well you will need to identify it and replace it. Cleaning up the board around the burn can be achieved with a fibreglass pencil.
rgds