VECTOR: TECH: Tempest Mathbox "M" error

 Well, the Tempest board that I posted a tech question to the list about the
other day lasted about 15 hours before dying again.  I do have a spare board
on hand which makes troubleshooting a bit easier.  The main board seems to
have blown out the XY circuitry again (the TL082 and/or MC/SG1495s).  The
AM6012s are good as my PCBs are socketed there and I can swap the chips to
my good board set to test.  I am going to socket the TL082 and MC/SG1495s
this time around and we'll see if replacing those fixes the main board
again.

 The AUX board on the now bad PCB set I swapped over to the good PCB and now
get a "M" mathbox error on the self test.  I've swapped all of the socketed
chips on the AUX board with those from my good AUX board and still get the
"M" error.  I've reflowed solder to the interboard connector plugs and still
get the "M" error.  Any ideas on where to start on with one?

 Thanks in advance!

-Steve P.