Good article Bill, well documented as usual . . .
Another way to use the "conductive paste" repair material is to use a toothpick. Apply from the tube to the toothpick and then transfer that to the ckt trace. You can make a much smaller line that way. Make sure to CLEAN the area with alcohol first especially if there's damage as shown in the video.
Graham, I would repair the traces using fine (30 gauge) wire-wrap wire. Clean the trace; use some liquid solder flux and lay the wire across the gap.
Using a soldering "station" iron (not a Radio Shack blunder-bus iron) set to about 600 degs, simply touch the wire with a tinned iron, and it will instantly flow and make a very, secure repair.
Put it this way, passing heavy current through that path will not open at the point again . . . ever!