It's been a while, so the details are a little fuzzy. But, basicly, what you have to do is loosen the outer nut on the elevation turret, allowing you to get pass the detent & get additional adjustment. To loosen this nut, you need to make a spanner screwdriver from a large (hopefully, inexpensive) screwdriver by grinding out the center section, & hollowgrinding the outer sections that will turn the turret nut.
Once you get into it, this will make sense.