hi there.......led 3 is current limit on motor.......will activate when lift stalls or excessive current is 16a for longer than 1 second...........first check for any friction between carriage,roller assembly and rail..the most common cause is the motor/gearbox you can check this with a clamp meter on the blue and brown motor wires..measure the start current and ensure 26a then it should drop below 16a for the run current if longer than 1 second at 16a lift will stall ...it would be a lot cheaper if you could purchase a second hand 300 carriage somewhere.........hoped this has helped......ian portsmouth...uk
ian, August 2012