There are two main kinds of springs, torsion and extension. Extension springs go along the tracks parallel to your ceiling. Torsion springs are wound around a bar that is above your garage door opening.

In most cases if one of your springs is broken it will be entirely impossible to open your garage door. The exception is if you have a single door and it is made of a light metal. In any case it is best not to attempt to open your door yourself. It might lead to injuries.

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While the average homeowner should by no means attempt to replace an torsion spring without specific training, extension springs are possible to replace. Replacement springs can typically be found in big box stores.

There are some repairs you can make in your garage door. One of the features of a garage door opener is that it has stop reverse lights that can stop your garage door from closing if something is obstructing its path.

At the bottom of the tracks on either side of your garage door opening, you will most likely discover a pair of stop/reverse lights. These lights are actually a transmitter plus a receiver of infrared beams. If the beam is broken your door will stop going down, turn around and go all the way back up. As a rule your garage door light will flash when this happens.

Does your garage go down, then back up for no evident reason? If you've carefully checked for an object in the way of the door and can't find anything, you may have bumped your stop/reverse lights out of alignment.

The main reason that your door will stop and reverse is that your "eyes" are working just as they are supposed to. There is something blocking your garage door. Sometimes whatever is blocking the door is not obvious, so carefully look around your garage door opening. Ultimately you'll figure out what it is.

If you've spent quite a time searching for the item that is blocking your garage door and nothing seems to work, try cleaning the lenses of your stop/reverse lights with a paper towel. Possibly a bug or mark has gotten on the lense.

Another cause of an unpredictable garage door is that your opener's logic board or gear sprocket has malfunctioned.

While a homeowner armed with an adventurous spirit and a certain amount of mechincal skill can replace a logic board and a gear sprocket, perhaps the easiest course of action is to merely call a garage door technician and have the difficulty taken care of.

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There are businesses that work on all sorts and types of garage doors. They may come to your property or business and carry out a complete repair and overhaul of your door if necessary. They exchange springs, rollers, tracks, sections, cables and whole garage doors.