Before you attempt to adjust it... Get a can of PB blaster, and hit the screw w/ it. The majority of times it will break off, and leave you to stuff rags behind the headlight.
It's mostly a non issue, but you have to loosen the debris/rust first.
What I hjave ALWAYS done is line the biik up on a darkened wall, and mark (w/ tape) where the center of the beam is (top/bottom). That should be a bout one foot of space between the tape marks. Then you have a guide line to judge from.
If the beam is too high while riding then SPLIT the difference down/ too high... split the difference up.
Don't be scared... Lube it, and measure it. (that's what she said) Just heading off the obvious jokes.
Edit... I corrected the mis-spallings. Thair wur a lots of themm.
