The older Overhead replacement remotes below use 12 switches like the two position block shown below. Matching the switches in the remote to the receiver sets your code.
Set the twelve-digit toggle code switch to match the code set from another functioning transmitter. Access to the remote toggle code switch is achieved by removal of the back cover and battery (if necessary). Move switches using a small pointed object, such as a paper clip, gently switching the small switches to either the ON or OFF position.
Compatible Replacement Remotes Are Included Below.