The latch sits inside the print head assembly. It holds the print head firmly in place ensuring it makes contact with the ticket stock at the time of printing. If the latch fails the head cannot burn content onto the ticket stock. It can look like one side of the printed ticket is "faded" or blank.
The latch has a smooth top with a nub that protrudes for easy movement. Below the flat surface, there are clasps on opposite sides of the latch. These are used to hold the latch in place. One side has a small pressure spring that allows for the clasps to be moved and makes for easy removal.
When the latch fails the nub disconnects from the top as seen below.