I have 2012 Volvo S40. At some point, something has scrapped against the window and broken a few of the grid lines. The result is that part of the defroster grid does not work. Most of the window does defrost, it's just around the lines which contain a broken connection that it doesn't.
How can I fix this? I've seen some conductive paint/glue products to repair the individual lines, but I'm a little sceptical from the reviews of such products. If this is the best solution, I'd appreciate any suggestions of ones to avoid and try.