Have a 1963 that the left brake light will not work. The tail lights work as do the turn signals on both sides, but the drivers side brake light won't. Obviously bubs are fine, brake switch under dash is working - checked wiring to the lights and all are good - free of shorts. I have an electrical diagram of the car and it looks like the brake lights go through the turn signal switch? Any thoughts on where to troubleshoot next? Thanks!