You should be able to twist the lever in a clockwise direction while it's open, which will tighten it a bit into the nut on the other size, then once you have it in the right position again, you can tighten the lever back down and it should be more secure on the rail.
Trijicon provided easy way to tighten or loosen; it is a breeze.
Open lever, push lever in towards mount, bolt will protrude out back of mount. Turn bolt ONE FLAT at a time and check tension. It really was that simple; gotta love Trijicon!
Open lever to release position, push lever in towards mount, bolt will protrude out back of mount on other side. Turn bolt ONE FLAT at a time and check tension