Rowland Heights sits in a mild temperate band, so you're not dealing with the freeze-thaw cycling that cracks nylon rollers elsewhere or the extreme heat swings that warp track. What you are dealing with is age. A house built in 1976, which is close to the norm for this area, has had roughly fifty years of one door opening and closing on the same steel rollers it left the factory with. Steel rollers don't fail dramatically - they wear gradually, flatten on one side, and start rattling in the track long before they seize. Across 15,011 households here, a lot of garages share that same timeline, which means a lot of doors are due for this exact fix around the same age, not because of any one storm or season but because the hardware has simply put in its years.