Your garage door sees a great deal of wear and tear through its normal operation, as it is exposed to lifting heavy weights and the elements throughout the year. Over time, this can cause damage and stress to many of the internal components that are used to operate the door. Damage to your garage door springs in particular can be dangerous, since they are under high pressure and help hold up the entire weight of your garage door. This means that any sort of damage can be a serious safety concern. Understanding the signs of damaged garage door springs can help you determine when you need to contact a contractor to have your door serviced.
One of the earliest warning signs of spring damage, and also one of the easiest to notice, is if your garage door is suddenly much louder when it opens and closes than it was before. This is more than the usual rattling associated with the chain or the garage door opener's motor: damage to the spring will create a loud bang, pinging, or a similar sound. This is the sound of the spring itself either breaking or stretching to the point where it is no longer stable: in either case, it will likely need to be replaced by a professional.
Failure to Open
Another warning sign that you garage door springs have broken or have become seriously damaged that is fairly hard to miss is if your garage door gets stuck while opening. Your garage door will only be able to lift about a foot or so from the ground: the fact that it will not go any further is actually a safety failsafe that prevents the opener from lifting the door any further, because the springs do not have enough pressure to hold the door in place, and it would be at risk of suddenly falling.
A spring that has become worn or is otherwise reaching the end of its lifespan will begin to slowly stretch: a normal spring should be tightly wound, without any gaps between the coils, so any signs of separation is a cause for concern. Once the spring finally breaks, those gaps will be even more obvious, as the spring will separate into several pieces, and will no longer be able to hold any tension (which means that your door will likely be stuck in place as well).
For more tips, check out sites like hungritedoor.com and contact a local garage door company.