These are the pilot adjustment screws, screw in old ones, counting how many turns out they were (may need the "D" tool Newbonneville.com also sells), take out the old ones I think there is a spring there also you will need to reuse, screw in new ones all the way and then out same number of turns as old ones (you can use your fingers for this). There are grooves deeper than knurl 180 degrees apart on new screws, painting one of these grooves with finger nail polish, permanent marker or something similar will help in counting turns to back out.