I have double gates and the slave gate isn't working

Run the actuator arm direct from a 12v battery. To extend the arm, place the red cable to the positive and the blue cable to the negative on the battery. To retract the arm, place the red cable to the negative and the blue cable to the positive on the battery.

If your actuator worked direct from the battery go onto step 2.

If your actuator didn't work direct from the battery, then locate the end of the 1mtr of cable attached to the rear of the arm and run it direct from the battery. If the actuator works, then this tells us that your cable across the driveway is damaged and needs replacing. If the actuator still doesn't work then you may require either a new motor or complete new actuator arm.

Your slave arm will be wired into MTB on the main control board. To test if the issue is with the control board or the actuator arm, swap the MTB and MTA cables around on the board (see image below). Does the issue stay with the slave arm or is the arm closest to the control box now not working?

If the issue has now shifted to the arm closest to the control box then you will require a new control board. If the issue stays with the slave arm and you are confident that the cable across the driveway is in good condition, then you will require a new actuator arm.