Troubleshooting a servo motor

I hate to admit this... I'm at a loss for figuring out if a servo motor is bad. A regular motor can have a megger-test. What does a servo have?

I'm working on a automated saw that matches a line speed with an encoder, and uses a control logix PLC to control a servo drive and motor to move the tabletop at the same speed while the saw cross-cuts the material. The servo stopped working and I'm trying to figure out why. I'm watching the ladder logic and during the "homing" function, the "IP" lights but there's no movement from the servo. I'll be checking one more issue that might be keeping the servo output from being turned on, but if that doesn't bear fruit I'll be looking at the possibility that the servo is bad.

Any insight?

Problem was solved. It was another reminder not to get too focused on electrical. The problem was a broken belt. A chat with the operator... "I could move the table top manually" raised a red-flag that the issue was not with the motor. A flashlight ended up being the only troubleshooting tool needed.

I have found 95% of electrical "problems" are caused by a mechanical issue!

Anyway if you have a servomotor with permanent magnets, you can disconnect the motor, then joint the three fases of the motor and try to turn motor with your hands. If motor is ok motor it should be difficult to rotate. This is one test I guess there mut be others.