Garage door springs are a prime candidate for air spring conversions. Yes, they'll require more services, and yes, more expensive, but a lot easier to wrangle.

Garage door springs are a prime candidate for air spring conversions. Yes, they'll require more services, and yes, more expensive, but a lot easier to wrangle. Alternatively, you could package a counterweight that would do the same thing. I recently helped a neighbor with his broken spring mechanism (old 60s house in San Francisco). The whole thing was made out grossly inadequate metal which had sheared. What started out as a simple welding project turned into substantial reengineering just to get the door to work to get his car out. Final lesson: steel fatigues and cracks from work hardening and bad tolerance installation. If you have an old door mechanism, don't trust it. Replace it. They're moderately expensive, but the modern ones are not nearly as hanky as the older ones. Don't DIY a garage door unless you have good levels of hands on fabrication experience and a good practical knowledge of what type of fasteners to use to anchor the door hardware to the building substrate. (I.e. Deck screws won't work.)