Motor Running But the Door Not Moving? Usually a Stripped Gear

Stripped drive gears: the opener failure we see most in Perth

Inside most residential openers a hardened steel worm on the motor shaft drives a nylon or plastic gear. The plastic is the sacrificial part by design. Heat in an uninsulated Perth garage, factory grease that dries out after eight or ten summers, and a door that has drifted out of balance all chew the teeth off that gear.

The tell-tale is a motor that runs its full travel, sounds completely normal and moves nothing. Lift the head unit cover and there is white or grey plastic swarf sitting in the housing. Merlin MT and Professional series units and Steel-Line openers are the ones we regear most weeks, followed by older B&D and Gliderol heads.

A gear and sprocket kit takes about an hour. We fit the new gear, repack the drive with the correct grease, reset the limits, then check why it failed, because a heavy or binding door will destroy a new gear just as quickly as it destroyed the old one.

• Motor runs, door does not move: the gear has stripped
• Plastic swarf inside the head unit confirms it
• Gear kits carried for Merlin, Steel-Line, B&D and Gliderol

Logic boards, capacitors and limit switches

When an opener is completely dead the usual suspects are the transformer, the main logic board or a failed capacitor. A board hit by a lightning surge will often still power the courtesy light while ignoring every input. Perth's summer storms produce a wave of these calls every January and February.

Limit switches decide where the door stops. Mechanical limits on older heads wear and slip, so the door stops short or drives into the floor and reverses. Digital encoders on newer units lose their position after a power cut and need re-learning rather than replacing.

We test the supply, the board outputs and the safety circuit before condemning anything. A board is worth replacing on a unit under about ten years old; past that, a new head unit is usually the better spend.

Belts, chains, rails and trolleys

Chain-drive openers stretch. A chain that sags more than about 15mm below the rail is loose enough to jump the sprocket and will eventually damage it. Retensioning is a five-minute job; a chain stretched past adjustment gets replaced.

Belt drives are quieter and common on newer Perth homes. Belts fail at the trolley connection or fray along one edge after years of sun through a garage window. The trolley itself has a plastic release mechanism that cracks, leaving the door disconnected from the motor even though the carriage still travels.

Bent rails, usually from storage being hung off them, make the trolley bind at the same point every cycle. That shows up as a door that hesitates in exactly the same spot each time.

Repair or replace: how we decide

A gear kit, a capacitor or a limit switch on an otherwise sound motor is worth fixing every time. It is a fraction of the cost of a new opener and the mechanical parts around it are unaffected.

We suggest a new head unit when the motor windings have burnt out, when the board and the gear have both failed on a unit over ten years old, or when parts for that model are no longer made. Swapping a failed opener for a new one is repair work we do; installing brand-new doors is not.

Either way you get the honest version on site, with the cost of each option laid out before anything is ordered. If a repair will only buy you another six months on a tired unit we will tell you, and if a ten year old opener still has plenty of life left we will tell you that as well.