I bought this motor for a project, but I am not able to see which wires are 5V, GND, sensor A and Sensor B for the encoder. Is there anybody here that know this motor?
It seems as if your motor does not have the encoder on the motor. There should be soldered something to the 8 pins in the middle. Has that been removed ?
An optical encoder might be IR diodes with a disc with teeth, like it was used in an old mouse, encapsulated against dust.