I purchased a makino rmc 55 from a company that bought it in 1992 for a high volume job. The job got cancelled and the machine sat on the floor until it got pushed to the back corner and forgot about. the mill sat untouched for around 7 years. I got it home and hooked it up. everything powered up and the last program was still loaded in the control. the x and y servos ran smooth but when i tried the z it would rotate about 90 deg then start to shake and vibrate until it caused a servo overload alarm. i pulled the servo to see if the ball screw had frozen but everything on the machine was loose and working fine. with the servo out it does the same thing. rotate it back and forth 90 deg but past that and it starts to vibrate and jump until it throws an alarm. the control is a fanuc om and the servo is a 10s. i also checked to make sure the brake was releasing and it seems to be. If i rotate the servo at highspeed using the handwheels it will turn 360 deg but it jumps twice every rotation. Is this a bad servo? or could it be something else like a bad feed wire or missing parameter? If someone has run into this before or could give me an idea of what to look for it would be much appreciated. Thanks in advance to anyone that takes the time to read my trouble and tries to help.
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