Mazak VCN 510-C motor encoder question

Greetings.

We are facing an issue with the spindle motor (Mitsubishi).
We have changed the bearings as we got an alarm
for spindle malfunction,
and as a result there is an error on the encoder.
When we try to rotate the spindle (even by hand)
we get immediately an alarm and emergency stop.

What I am looking for is some information on the encoder
of a sj-4-vks15-13zt motor.
Do they sell these separately or together with the whole motor?
Do I have to contact Mitsubishi or Mazak for this?
Any idea/suggestion?

Thanks a lot in advance