One of mine broke as well. Went in and had a chat with our local garage door guys, and they were very helpfully. Basically they said that for residential, the springs are good for approximately 10,000 cycles, and that to keep everything in balance, they should be changed in pairs. They determine the size of springs required based on the weight of the door. About 100 bucks for all the parts up this way. Definately NOT a job for the clutsy types amoung us. Its not just the spring assemblies that have to be rewound, the cables on each side of the door have to be positioned correctly as well, so mark those with a marker before disassembly. Mark the distance from the end of the rod, and the relative position of the wheel position on the rod as well. It will save you some grief as your trying to put it all back together. Oh, by the way, I changed those cables as well at the same time because they were only about 6 bucks each. If your doing it yourself, be very careful. And make sure you remove your vehicles from the garage before you start, if you can get the door up to get them out. I lubed up all the rollers and track with fluid film, and it rolls much quieter. Good luck, and again, be very careful.