Headlight switch shaft/knob won't click and lock in.

The taper end of the stem is supposed to draw the latch to align its hole then the spring brings the latch into stem holding position. If you push the release button without the stem in place you can push it too far. Then enough force on the stem while the latch is pushed too far can distort the other side of the latch. If it's not already screwed up...Put the stem in and push the button slowly may help