[quote=ltsdd]This is one of those repairs that I wouldn’t recommend to DIY. I had mine replaced a few years back at $90/spring + $75 labor. The safety risk alone was enough to convince me to pay an extra $100 bucks or so to have it done by a professional. Also, I know for sure that I wouldn’t know what the proper tension to put on the springs for it to operate correctly and safely.[/quote]

It’s actually pretty easy to figure out the correct tension now that I’ve done it.Open the garage door about 3 feet. If it stays without moving, it’s about right. Then open the door fully. Check if the two side pulleys still have tension. IF they are really loose or unraveled, the tension isn’t correct.

I think the two biggest safety thing to keep in mind is.

(1) when you wind the spring, don’t stand right in front of the spring and don’t get in the way of the winding bars if you lose your grip and it springs back.

(2) Go overboard and wear a motorcycle or auto racing helmet on top of safety glasses that you should also wear.

I’ve done a lot worse at other things. When I was torquing down my miata’s supercharger, I managed to jam my long/heavy torque wrench on a bolt. I started to pull really hard to get it out, and then when it was still jammed, I used all my strength to pull it out. Obviously, me winning the darwin award that evening, I didn’t have my safety glasses on, and that wrench came loose and went full speed right into my face and hit my upper left eyelid. Fortunately, I only ended up with a big bruise on sclera, and didn’t hit my pupil or my iris.
It was kinda cool, I didn’t know you can get a bruise on the eyeball. The eye doctor said i was lucky I didn’t it it lower. Looking back at it, I think this would have been one of those Darwin YouTube videos that ends with me saying “hey, watch this…”