Other things I have tried was to switch the M80 with the issue to the channel and connections of the M80 without any issue and the problem is still there.
Is that the same speaker or the same channel? If it is the same channel then the problem is not the speaker but the amp or the pre/pro. If it is the same speaker then I would suspect the problem is in the crossover considering you have already swapped the tweeters out.
You really should rerun Audyssey or stop using it if it is setup for you old speakers, as the previous EQ is most likely not really helping the Axiom's sound the best