the mill seems to be back to normal aside from the need to put it back together . I air cut for a few hours last night and the mill is behaving
The more I think about it the loose connection at the power supply is the likely culprit . I heard a pop when one drive blew and an arc is probably what I heard . This was the first time that cover has been off so I can't even guess at how long that power wire has been loose .
I like the mx drives but they are obviously a bit overly sensitive at times . The estop blowing the unit is well known and it's possible a power flicker mid run is enough to blow them to , but who knows ??

There is a distributor who sells individual replacement boards for the axis in the mx3660/4660 . At least leadshine is wise enough to allow a customer to repair a blown axis rather than replace the whole unit . I contacted the distributor yesterday to ask if they can also source the top (breakout) board but I got no reply . I'll probably go to the horse's mouth and try leadshine usa .
Still no reply to my inquiry from tormach either as expected . I'm sure they have a short list of possibilities and I was hoping for some input because this has become a tad costly .

it's too soon to say it's a problem solved but I'm hopeful