Opener parts — identifying gears, capacitors, boards and rails

The model label carries the model and serial number, and on most brands the serial encodes the manufacture date. Parts diagrams, gear kits and boards are all indexed by that model number — from the label, not from memory, because families of near-identical openers differ internally.

The learn button colour identifies the radio system generation, which is what actually governs remote and keypad compatibility. The same nominal model shipped across more than one radio generation, which is why the button outranks the model number for anything wireless.

With both photographs, a parts counter or a search can produce the exact gear kit, board or remote. Without them, the process is guesswork with return postage.

The drive gear. On chain and belt units the nylon main gear is the designed weak point, and it announces itself unmistakably: the motor runs at full speed and nothing moves, often with white shavings dusting the inside of the housing. A gear kit — main gear, worm gear, grease, retainers — is indexed to the model number and is the classic repair.

The start capacitor. A motor that hums for a second and gives up, or needs a spin to start, is usually the capacitor. The replacement rating is printed on the old can in µF and volts; match both. It is one of the cheapest real repairs on the whole door.

The logic board. Surge and lightning kill boards, and the symptoms are erratic rather than absolute — intermittent response, lights flashing in patterns, phantom reversals. Boards are model-indexed and often shared across brand families, which is where the cross-brand relationships on our brand pages save real money.

The trolley — the carriage the door arm attaches to, with the red emergency release hanging from it — is drive-specific: a chain trolley, a belt trolley and a screw-drive carriage are different parts entirely. Identify the drive before ordering.

Chains stretch and belts wear where they wrap the sprocket; both are adjustable at the trolley up to a point, and replaceable as model-indexed assemblies past it. A screw-drive carriage that grinds is usually a dry rail first and a worn carriage second — lubricant rated for screw drives before parts.

Photo-eye sensors are the one opener part best bought as a matched pair for the same brand generation as the unit — mixed-generation sensor pairs are a steady source of doors that close only sometimes, which reads as a haunted opener and is actually a parts mismatch.