I also tested all the speakers I had. Pretty good outcome with only 1 bad one. It works but barely. I am assuming it has 'popped' as we used to call it 40 years ago. Probably could be repaired but not worth the effort. I do have 2 that will need the cones glued. Small puncture holes. I will do this with watered down wood glue which seems to be the recommended method. Holes are small, and the speakers work fine, but I don't want them to degrade.
Testing the C70 speakers were a real pain! Every speaker has a different connector and the wiring diagram I have is wrong in several areas in terms of wires changing color along the path, and 2 speakers having the same wire colors?? I had to make up flying leads for every speaker to test them. All were good!
Today is tidy up day as I have a mess on my workbench and need the space to repair my R dash mounts. It has been a somewhat challenging project but very satisfying to get it working. Now have to find time to get homes for all this stuff!!
Neil.