Align the fiber in the sight window and tighten the set screw to hold it in place. To contain the loose end insert the loose end into the hole, locking it in place with another 4-40 set screw. Trim any excess fiber and tubing with a pair of side cutters or sharp blade. Carefully bend the fiber and plastic tube, without kinking, the fiber. This can best be accomplished by cutting a sharp point to the fiber with a pair of finger nail clippers or sharp blade.
Gentle pressure works best.
Let the fiber extend out the front of the tubing and trim it. Polish the end by heating a flat blade and touching it to the end of the fiber. Insert a brass bushing from the kit into the hole the fiber is to be installed in and hold it flush to the outside of the aperature. Hold it in place with a 4-40 cap screw finger tight. Insert the free end of the fiber into the brass bushing from the inside of the aperature until the stainless steel tube is inside the brass.