Probably a mechanical issue, motor or gear reducer.
Has the grease ever been changed? I suggest you find the bad component and replace it. Also make sure to change grease per the manual.
Should be smooth. Could you move that joint on arm smoothly with no motor attached?
Sounds like a new servo motor is needed.
The brake needs power to release. Are you sure you tested it correctly? Also If everything is powered, then the brake would release but the motor would try to hold position.
I'm not sure if you have ruled out a bad reducer.
If that is the only motor you removed/unplugged, then you can zero master just that axis by aligning it to the witness mark.
Ok, that test sounds legit.
By removing j4 motor, you will now have to remaster it also.
You can master at any known position, so those values are probably from the factory fixture master position, which you don't have. So, you will have to find the witness marks and change it to zero for mastering.
Your mastering will probably be slightly different from factory so you will likely need to touch up all points after you are finished.
Jog J3 and J4 in joint 1 motor rev to establish a pulse. Then jog to witness mark. You can do them 1 at a time for mastering.
0 for master pos. Then enter 1 under SEL. Then execute. Then calibrate.
Once you disconnect the motor from the axis you have lost the original relationship. So quick master will not work.
