You loosen the locking inner nut and turn the outer nut clockwise to adjust the excess slack from the chain.
Garage door chain tight one side loose other chamberlain.
The trolley is responsible for pushing or pulling the opener arm along the chain so as to open and close the garage door.
Step 2 turning off the power.
Tightening your garage door chain is a simple matter of turning the right nut.
Adjust it tight enough so that the center of the chain sags about 1 2 down from parallel with the track graphic below right.
Do not over tighten the chain.
The one you re looking for is attached to a bolt found at the spot where the trolley or carriage connects to the rail.
If in doubt replace the chain completely.
Once you are clear that the only problem is a slightly loose chain then you can begin fixing the problem.