I realize that this may be an ignorant question, but here goes. I have an 1986 M1009 Blazer, and I've been having a helluva time trying to replace the headlight knob. The dang thing just won't click into place. I've already bought a new knob and new switch, tested the two in the store, where they clicked together fine....but can't seem to do the same thing when it's in the truck. Any help out there? Thanks!