I could not be happier with the service from Precision, and Tom, especially. About a year and a half ago I called to have my garage door that was sticking, repaired. Tom came out same day and replaced, adjusted, serviced all moving parts and got it going smoothly. He has since come out within hours of a call to adjust and keep (what might not be the best) door, (originally installed by someone else), operating well. I recommend Precision and Tom with complete confidence.
This is the electric opener which operates this door. I'm picturing it here because you pull the rope to disconnect the trolley, run the trolley under power to the fully-open position, and then disconnect power before working on the door. Then you should lock the door down with either the security lock or with Vise-Grips or C-clamps. This avoids the door lifting when you don't expect it as you are applying spring adjustments. It you were to foolishly overwind the spring without the door locked down, you could possibly find the door trying to leap up to the raised position when you aren't prepared. That would likely knock your grip off the winding rods, with potentially disastrous results. I like to work under the safety principle that serious accidents should be physically possible only when you make two or more stupid mistakes at the same time.
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Luckily, there is a bit of science to questions of garage door repair and replacement. That’s why we’ve put together this guide on when to replace a garage door. We’ll prepare you to compare repair vs replacement garage door costs. We’ll discuss the ways in which repairs are the most affordable option while also exploring those moments when replacement will in the end provide you with more value added.
Additionally, the B970 includes encryption features that prevent others from hacking the system to gain entry to your garage. Expert reviewers like this garage door opener a lot. The Tool Spy says the Chamberlain B970 justifies its higher price point by delivering excellent build quality and anti-vibration features. Consumer Search and Garage How To also approve of this unit.
Beware of improprer prior installations: Sometimes the existing door installation is not correct, and the old springs should not be used as a specification for replacements. For example, the old springs might have been replaced with incorrect sizes because the last repairman didn't have the right one on his truck. If your door has never worked quite right, something like this might be the cause. To correct this, you must use the weight of the door to specify the spring, either from a spring rate manual giving spring torque constants, or from the formulas below.
Another moment of truth arrives as the winding-up of the springs begins. (I am just posing here with the camera held out in my left hand. Except for lifting the door onto the scale, this was a one-man job, including the photography.) The position of the bars in this photo was necessary to take the photo, and does not show a correct winding technique, You should not have to swing the bar up as high over the top as shown. The lower bar during winding should swing from pointing down to pointing a little past horizontal. Then you hold that bar horizontal while socketing the other bar pointing down, apply force to that (now) lower bar, then remove the (now) upper bar, wind one-quarter turn, and repeat.
The standard winding tools are simply a pair of 18-inch lengths of mild steel rod, 1/2-inch diameter. Winding cones can have different socket sizes (such as 5/8 inch instead of 1/2 inch), so it is important to measure the socket and select a matching rod diameter. Also beware that poor-quality cones may have a sloppy fit to the winding bars, and a loose fit presents a severe hazard of slipping at the worst moment; anything more than about an inch or two of play at the handle end is too loose for safety. I bought a 3-foot length of zinc-plated 1/2-inch diameter steel rod from Home Depot for about $3, which conveniently cuts into two halves of just the right length (the store might even cut it for you if you ask). A steel supplier selling at commodity prices might charge about 50 cents or so for such a piece that weighs about 2 lbs. Drill rod would work if used in the annealed condition in which it is originally sold, but the added expense provides no benefit and the brittleness (if it had been hardened and not annealed) would worry me a bit. Rebar, threaded rod, screwdrivers, etc., are absolutely foolish as they will not fit the socket snugly. Aluminum rod is definitely too weak, and will bend under the torque that must be applied. Longer rods would make for more leverage but unwieldly swing; shorter rods make for uncontrollable swing. As we'll calculate below, the 18-inch standard tool length is an appropriate compromise. Note that you do not need 18 inches of ceiling clearance above the torsion shaft to use an 18-inch rod, since you need not swing the rods above horizontal when winding.
Here are the new replacement springs I ordered from a distributor, which I found using a Google search for "garage door supply" (search that phrase now). You certainly won't find these at Home Depot or Lowe's (although last I checked Lowe's does carry the less daunting extension spring replacements). I also have a list of some suppliers at the end of this page.
First and foremost, a garage door, by design, contains springs designed to balance your door and make it easier to lift. Those springs are under incredible amounts of tension. If a spring breaks or is improperly released, it can cause incredible and potentially fatal injuries. Keep in mind, when working on a garage door spring, it is likely that your face and head will be close to it, meaning that your most sensitive area will be in the direct path of the released spring. 

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