It might be necessary to pull the door closed slightly to fully engage the trolley.
Overhead garage door engage and disengage.
Some garage doors do not have a manual lock once disengaged from the garage door opener.
The opener trolley will engage the carriage once it comes to the full open position.
To disengage you ll pull the emergency release cord down which will release your garage door from the opener system.
Make sure the carriage unit is nearest to the garage door.
Pull the release rope and push the door all the way up until you hear a click.
Push the control button either on a remote or at the wall station to operate the garage door opener.