First and foremost you should never try doing it yourself when it comes to your garage door spring system or cables. There is an unbelievable amount of stored energy contained in your garage door spring system. The risk of serious injury is very high!! This post in intended to give some basic safety pointer in the event that you experience an issue with you garage door system.
The most commend failures to occur with your garage door is a broken spring and what we call in the industries a hung door. A broken spring is just that, the wire coil that makes up the garage door spring separates releasing the tension form the spring. 99% of the time this happens to a spring that has reach it cycle rating and will occur in the down position. Most two car garage door spring systems use a dual spring system and just because one of the springs has broke there is still quite a bit of tension on the spring that is still intact and the cables, located on either side of the garage door. Trying to release the spring tension on the spring that is intact or removing the cables can and most likely result in an injury. I still situation make service that children and animals are not near the garage door and call a garage door company for service.
A hung door is when one of the cables has come off a drum causing the cable to be longer on one side and making the door crooked. This can be cause by many different factors such as springs starting to ware, the door being closed on something or underperforming rollers just to name a few. It is very important not to touch the door when it is in this condition especially if the door is not fully closed. Trying to force the door down can cause costly damage to the garage door and garage door opener and also can cause panel or the whole door to come down. In this situation keep people pets and property far away from the garage door and call MasterCraft for service.