Is it confirmed whether it is the motor or encoder?
The reason is that they can be replaced separately, also if you search ebay you will find many, A06b-0142 motors, the B110 is the encoder type and whether brake or taper shaft.
If it is the motor, you can take your existing encoder off and put on another motor, the other scenario is if you can locate a motor with the same encoder and take the encoder off for yours.
For e.g., there is one motor that appears to have the same encoder, #220645973470
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.