The Genie Coupler Is Used To Connect The Motor To The Screw Drive Rail, So When Your Opener Is Running And The Screw Is Not Turning The Coupler May Be Bad. There Are Two Different Couplers Made. The Genie Screw Drive Coupler, 30257T.S Is Used For Older Screw Drive Units. This Coupler Has Both Hole Sides Of The Coupler The Same. The Genie Screw Drive Coupler, 36645R.S Has A Larger And Smaller Hole On It.