gregvisser,
Glad I could help.
That screw wont help your fletching to come out even. Are they all uneven the same? The only time that has happened to me I grabbed the base of a feather with the clamp instead of the feather itself (at least thats what I think) & it threw the one feather off a bit.
The screw allows you too turn your nock in relation to your fletching a bit. I fletch cock down like you but if I put the cock feather on perfectly square the front of my feather or vane will hit the left prong on my rest. The screw loosens the nock holder so you can rotate it & not move to the next click stop. A little goes a long way & its easy to go too far. I usually will try an arrow with a loose nock first & if its not quite right I can put the nock where I want it & try using it as a guide to adjust the nock setting. Its trial & error but once its set its done & switching from feathers to vanes doesnt affect this setting.