re: Garage door experts - torsion spring question.

I did a little more research and I found the website of the company where I bought my torsion springs 8-10 years ago: DDM Garage Doors Torsion Springs FAQ page

DDM has lots of information about changing the springs yourself and your options on springs, one or two springs, converting to two springs, how to determine what size you need, and different life cycle options based on size of spring. The torsion spring table is at Table for Torsion Spring Options.

My garage door opener was recently fried by lighting. While it's being replace, I could lift and lower my garage door with one hand and about 3 pounds of force. DDM's website helped me find the correct springs for my garage door instead of the set of springs the installer happened to have on his truck.