This can be caused by two different things.
Stanley garage door opener chain loose.
Chain adjusts by moving the opener trolley guide tube or rail.
Garage door opener is very strong and seldom does the chain actually break.
One of the problems can be with the travel length of the garage door opener itself.
The chain connects to a threaded anchor that you can move in and out to tighten or loosen the chain as needed.
Another problem that might cause this is a malfunction of the electronic eye.
A sagging chain is a result of normal usage of the garage door opener.
Adjust the amount of travel in the system to keep the door to a specific stopping point.
You may find that a loose garage door opener chain has less power to open and close your garage door or you may find that it is just hitting the door as it moves it and creating an annoying sound.
If you find that your garage door opener chain has become loose with time you may want to tighten it up in order to remove some of that slack.
In this case the cable can be replaced fixing the problem.
Don t overtighten the chain.
This is common on the stanley chain drives that utilize the tubular style track graphic below.
Because chains are lubricated with grease you can expect to get a little dirty while putting the chain back on your opener.
Sometimes the cable will break if it is a combination chain and cable drive system.
You can put the chain back on your automatic garage door opener using a simple adjustment mechanism.
Same rule applies concerning recommended chain slack.
Watch this video and see the professional at town country door llc demonstrates the.