[yogi_123rd]

I believe you have two seperate issues.

Yes, scratched lines in the defogger will stop the defogger from working. The lines are made from metalic paint and is part of the circuit. It acts as a mini heating coil. A volt meter can be used to find breaks. If you have a break, it can be repaired. Parts stores sell a defogger repair kit consisting of special metalic rich paint to bridge to gaps.