I looked in my '67 FSM and if the circuitry is the same for '69, the fuse for the instrument panel lights feeds the lights directly, the fuse for the tailights feeds the headlight switch directly. If you have a voltmeter, check for voltage at the tailight fuse and the instrument panel light fuse. No power at tailight fuse, problem is before the switch. Power at the instrument panel light fuse, switch is OK and problem is in the dash. You can fill in the other possibilities. A little troubleshooting is easier than tearing the whole dash apart.

(Don't feel bad, I have to pull the front seat out to work on anything under the dash)