Symptom #1: Leaving for work in the morning, hit the garage door button, the light on the opener comes on, but nothing moves. So you try it again, same thing, there is noise and the door is not opening Most likely your gear kit is out. The gear kit is a plastic gear that enables the motor to drive the door up and down at the correct speed. If you remove the cover on the opener motor unit, there will be white shavings or the sprocket falls to the ground.
The gear kit is a fail-safe and ensures that no additional damage is done to your overhead door in instances where the door is froze down or hits an obstruction. It is much easier to replace a gear kit than a section of a door or an entire door.
Symptom #2: The chain falls off opener or there is major slack in the chain. This is because the plastic gear is stripped and a shaft bearing has most likely gone out. Thus, there is nothing holding the chain up. Need new gear kit.
PREVENTIVE MAINTENANCE. Garage door Opener gear kits are lubricated at the time of manufacturing. However, after years of use, the grease dries up and at around 10-12 years the gear dries up, becomes brittle and breaks. When you are performing your yearly overhead door maintenance, take the cover off of your opener and grease the gears. We recommend white lithium grease for this part. A gear kit can be replaced by a fairly handy person or call a professional to change it out for you.