The Genie AC Screw Drive models H4000, H4000-07, H6000, H6000-07 were very popular models. There are many of these still in use and running strong today. Above is a technical diagram showing the replacement parts for these AC screw drive models that are available here online. Once you locate the part you need you can see below for a description and the price. These replacement parts are made for do-it-yourself installation.
Parts not shown- Remote, Safe-T-Beams, Keypad (these are available below)
You can view the owners manual as well for programming assistance and maintenance information for the AC screw drive models.