This is very simple, but I thought I should share it anyway. Bugs might not be a problem during a high heat smoke, but since many have been using the A-MAZE-N-SMOKER, and doing low temperature smokes, there is a good possibility that all kinds of bugs could be walking into your top exit vent to visit the meat or cheese in your smoker.
I got a mesh sink strainer, and cut a slot in it where the adjusting lever is. Slip it over the lever, and center it on the vent. As you can see, it doesn't effect the smoke from escaping, and it doesn't effect your ability to adjust your vent. Works Great!
Cost ?---I forget---About $3, I think.
Smoke coming through vent: