Where did my Center Bearing go? The Sagging Garage Door
There are three bearings that hold the spring shaft in place and keep it spinning smoothly, one on each end of the shaft and one in the center.
Builder grade garage doors usually come with a plastic center bearing. As the springs age and get up to replacement time, the plastic center bearing has usually worn so badly that it splits into pieces and drops onto the floor, getting swept up and discarded in the trash. This leaves the center of the spring shaft unsupported, and exposed to breakage.
If the spring shaft breaks, bad things can happen as the hundreds of pounds of spring pressure suddenly release, potentially harming cars and people nearby.
Usually the center bearing should be replaced along with the springs to keep the garage door safe. Insist on a metal center bearing that will remain in place for the life of the springs. The end bearings should be replaced at least on every other spring replacement.