Thanks for the reminder, where is the set screw located? Is it in the side?
There are actually two of them. You have to loosen the elevation screw all the way up and rotate up the top half of the sight, you'll see the two set screws under there. If you want to make sure you can get back to your original elevation, count how many turns in you have to go till it is snug, and wright it down. That way when you put it back together you can snug it down then back it off the same number of turns. Also, keep an eye out while you are doing that there are two little springs under there, that tend to like to run off...
Thanks my tip, after drifting and counting the click, might re zero it again.