ALLISTER Garage Door Openers 009145 Idler Sprocket For Allstar, Allister, Pulsar and MVP garage door openers. Compatible with models ARD-II A, Access 200/250, Access 2000/2500, Access 3000/3500, PDQ, Allister Century Series 310/510/710 garage door openers. Older part number X-145 This part is located on the top of the main power head.