9.6 Bending the cable will help you avoid problems with the tip at the end of the cable catching on the end bearing plate and causing the cable to come off and the garage door to jam, cock, or fall. Check to make sure the cable is straight in the slot and not sticking out the side. Also the edge of the cable stop should not be pointing to the side as displayed. The cable tip should fit completely inside the drum, with the rounded part facing out so the tip can't scrape the end bearing plate.
In most cases, only one spring breaks or wears out at a time, and you can get away with replacing just the failed spring. But this is a little like replacing old car tires one at a time. You'll get the best performance if all the springs are new and have the same strength. Extension springs are replaced individually, making it more tempting to replace just one. With torsion springs, you have to disassemble everything to replace either spring, so it makes sense to swap out both springs during the repair.