here are my two cents.
You need to find out what kind of 24 V motor you have. If you know the brand name of the wheelchair you can try calling their technical service or consulting their manual. Otherwise, you may have to get access the motor and try to get the make, model etc. If there are no markings on the motor, you will have to find out if it is a brushed DC motor or a brushless DC motor by looking at the wires going into the motor from the controller. If there are just two wire, it is a brushed DC motor. if there are more than two wire (high voltage), it is brushless. you may also have hall sensors in the motor. If that is the case you will have at least three or more low voltage wires going into the motor.
once you have identified the motor type, perhaps you can get more help from this board.
just curious ...why do you want to replace the motor?