Unfortunately i didn't even need my tools. It was already clear by visually checking them that both window defrosters are toast, even if the glass was OK on both. The resistive threads have oxidated and vanished in large areas:
You can't really see it bot some of the threads are almost gone totally and there's only some leftovers from the original glue. Really wonder how that could happen. but it seems to be a common problem.
One of them even had one of the bigger threads loose. I know it's all repairable with stock-on thread wires, but not sure yet how nice i can do it and if it's worth the effort. Either i need a new glass or have it repaired by a pro.
Strange enough i figoured out i have both a vertical and a horizontal wired hatch glass. even if both my cars were built in late 1971. so either they were used longer than mentioned everywere, or it has ben swapped at one point in the past. strange enough the one with the vertical lines (the earlier version)is in way better condition with only one small area damaged and the rest still quite solid...