No idea on the production date, not even sure where to look, have to take a closer look at the serial numbers for a clue perhaps. To pop out the domes, I removed the 4 outer bolts first, then, when the tweeter is detached I removed the 4 inner bolts to part the diaphragm from the magnet. I then used my thumb and thumb nail to smooth back out the domes as much as possible, it takes a fair bit of pressure and I was worried more than once it was too much pressure. One did crack, perhaps a bit more thought about my approach might have made the difference but no way to know that now.
I was able to remove that white oxidation easily and it does not appear to have any issue visually on the connectors, no chance since last post to even listen let alone get out the volt meter again to do any diagnostics. The cone moves freely though, no sign of any rubbing voice coil etc. Also, I did not measure the impedance of the dome, I noted the 16ohm impedance on the magnet, but imagine the same? I'll research more on using resistors to match impedance, might be my only shot to get 4 matching new dooms, although the ones at $39 with many available are 4ohm.