This is a complex system which includes two springs, a set of four pulleys, two safety cables and two lift cables. The springs require a check for deformation and for thinning of the coils. In both cases, spring replacement is required. If the pulleys are worn, they should be changed as they can cause the door to become uneven and to go off track. Both types of cables and the lift ones in particular, should be checked for fraying and cuts. If any of these problems is present, the damaged component should be replaced as soon as possible. This system does not require lubrication maintenance to work properly.
This mechanism works with the safety sensors and without them too. This is because some objects may not be detected by the so called photo eyes. The testing of the reversal mechanism alone is a bit more specific, but it is an important part of garage door maintenance. It starts with opening the door. The key thing is to place an object which will not block the infrared beam of the sensors when placed underneath the door. This could be a double ladder, for example. The next step involves initiating door closing with the remote. The door should touch the object on its way down and then reverse immediately. If the unit hits the object forcefully to continue to the floor, then there is a problem with the mechanism. The opener should be fixed right away to prevent safety problems.