[M_Controls]

I have been trying to diagnose a problem on a 5-year old Milltronics Partner ML-20 CNC lathe, and I was wondering if anybody else has seen a similar problem, and the solution. I have been troubleshooting CNC machines for three years. The annoyance is that the machine will just unexpectedly enter "Error 450: Emergency Stop." Sometimes it happens when the machine is completely idle. It is in a medium sized metalworking shop and no other machines have intermittant control problems, the electrical system is only 6 years old, so I do not suspect the power source; and I have repetedly measured the voltage. The problem occurs approximately once a week, but is entirely random. Once it happened about 6 times in a day, then waited a month. I have tried monitoring the 24VDC supply but it failed to malfunction when I was monitoring. I have talked to Milltronics repeatedly about this, and they keep saying try the same things over and over again - without results. One suggestion tried jumpering over the limit switches to rule out the opening of said switches, and rule out loose wiring there as well. Another suggestion was to jumper over the e-stop chain to rule out this part of the circuit as well. These jumpers did not help, the machine still acted the same. I have reseated all the computer boards & plugs, and checked for loose connections and bad solder joints all over. This has been ongoing for over 2 years now. The owner says he is about to throw it to the scrap bin. In the last 9 months other bizarre problems have been reported as well. One was that the spindle just quit turning in the middle of running a program, and the machine axes just came to a stop, with no error displayed on the screen. I seen this result, the screen just showed the tool path, and it was just dormant in the middle of the cut. I opened the electrical cabinet and looked at the spindle drive, it was in Stop mode and no faults. Does anyone have any ideas?