For shafts to turn properly inside the end bearings, the end bearing plate must remain plumb. If the plate is not supported it can lean, causing the bearing or shaft to wear. Often a worn bearing will wear completely through the shaft causing the shaft and drum to drop and the garage door to become out of level.
Many of the bearing plates are flat and the horizontal track angle was not strong enough to support the plate, so additional angle was added. Here the bottom of the angle is bolted to the horizontal angle and the top is wedged into the jamb.
Another way to support a flat end bearing is the top of the flag bracket. On this door the drum was scraping the top of the flag bracket.
The simplest solution, without adding any angle, was to re-position the end bearing plate so the flag bracket supported the outside of the end bearing plate. Doing this may require moving one of the drums.
Another way to support a bracket on 12″ radius tracks is by wedging angle between the horizontal angle and the top of the flag bracket.
The support angle can also be bolted at the top and bottom.
One of the better inventions in the door industry for residential doors was the spring anchor bracket with the added edge that can be secured to the jamb. On 12″ radius tracks the top of the flag bracket supports the bracket. The top hole allows for an optional bolt but this is not normally needed on 12″ tracks if the cable drums are properly installed touching the races of the bearings.
On 15″ radius tracks, however, the top of the bracket must be secured. Normally a single 5/16″ X 1 5/8″ lag screw is needed, as shown here.
Sometimes additional support is needed as you see here where the top edge did not reach the jamb.
On one job a recessed I-beam prevented the normal installation and angle was run from the horizontal angle to the board on top of the beam.
Here is another solution where angle was added because the top edge of the bracket was above the header.