My '89 Fadal 4020 decided to start acting up today by faulting out the axis' and then the head slowly falls to the table. I reset the e-stop fault, return to "home" and the problem eventually repeats itself. What may be causing the head to fall down to the table? I can understand the axis faulting out and sitting idle (which it's always done in the past) but now the head falls and e-stop does nothing to stop it! Thanks in advance for any advice.