Originally Posted by
maver1ck
The "hum" you described could be from backlash. I have seen the coupling inserts on this vintage machine disintegrate causing a similar situation, but since you indicated the motor has been out already, I assume you would have checked/replaced the insert when it was out.
However, there are also many other possibilities. The A-608 alarm is essentially saying the axis has been at torque and current limits too long. There is a long list of possibilities for this to occur including motor, power cable, parameter settings, IR module, Mechanical issues, Encoder, Encoder cable, grounding, power section, control module, etc.