This control box is used on several model chairs, although mainly found on Golden’s and Med Lift’s heavy duty chairs.  It is needed to run both the lift motors together.  The box will have two 7 pin sockets that the two motors plug into, a 2 pin male socket that the cord from the transformer plugs into, and a 5 pin female socket that the hand control plugs into.  Many times, if you hear “clicking” in this box when the hand control is pressed, but the motors don’t run, then this is the problem.  Also, if one motor runs but the other motor doesn’t, then swap the motor plugs; if the one that wasn’t running now runs, then the box should be the problem.