This remote is discontinued. You can locate a receiver box above the drive unit R240 or somewhere near the ceiling around the motor . The external receiver's brand is Shima Digital that has harness with 3 wires: AC 24V connecting White wire(common), RELAY-Black wire and RADIO POWER-Red wire.
To replace the receiver is a practice solution. MK702T is composed of one receiver MR433 and two tyny remotes MK300 .
Undo old three wires and connect three wires of new receiver that's all you do it that couldn't be easier.
This one has been upgraded to MK702T.