Hello @akceelektronik
As Mr. Herbig and i stated, the normal Process is to send this Motor to the B&R Repair.
In addition for very special cases:
A skilled Application Engineer with some internal knowledge and the correct Hardware (B&R PLC with AS-Project and ACOPOS) can fix this issue on site. (Motor was repaired and due to this, the Encoder Mounting has changed).
You can get in contact with your Local B&R Supplier, and evaluate with them if they can support you in this issue.