Are you having trouble with your Liftmaster Garage door opener? Is the Garage door only closing if you hold the control button down? If so they most likely your safety sensor photo eyes are misaligned or blocked we suggest checking those first as that is the most common problems with garage doors not closing properly. What if your garage door is making noise but nothing is moving? Unplug the unit and take off the cover, if there is a pile of white plastic shavings in there then the drive gear is most likely stripped out. We sell the 41a2817 gear kit to correct this problem, sometimes its easier to change the whole shaft and drive gear also see the 41c4220 gear kit used on most of the Liftmaster chain drive garage door openers, we offer a great video to show you how to replace the gears on your Liftmaster garage door opener. We sell all of the parts for your door openers on our website. We have parts breakdown diagrams that show each part and allow you to order replacement parts quick and easily at a discounted price.