Yes, it's definately something in the horizontal sync section. I'm surprised that adjusting that pot didn't fix it.... did you try doing it with the monitor on? There's a small hole in the bracket to the right of the daughter board, you put a small screwdriver through the hole and it lines up with that metal can. You should be able to get it to snap in.
Usually if the horizontal sync is MISSING, the picture will scroll around all over the place. If it has those jagged lines, it's because the pot is misadjusted.
Ultimately like said above you'll need to recap the monitor and reflow the solder on the daughter board connections.