Make sure you have a wet paper towel or rag before installing your end caps.
Take your new end cap and insert it into the rail to see how the rubber tabs plug into the rail. Remove the end cap and clean both the rubber tabs and underside of rail with alcohol wipes.
Apply very small dots of Loctite 380 onto the tabs as shown. NOTE: Use very small amounts of loctite. Too much on the end cap will cause glue to squeeze out the top and onto your rail or end cap requiring more clean up.
Press up from the bottom of the end cap and press in at the same time using light pressure. Hold for 30 seconds and make sure you wipe off any glue that may have squeezed out of end cap immediately.
NOTE: It is advised to wipe glue off the rail while you are holding and pressing the end cap for the 30 seconds.