89 Regal Tail light issues need help please

I have an 89 Regal custom. Of the the 3 Brake lights (driver, center, passenger) The Driver side tail light does not light up when I hit the brakes but the others do. The tail light lights up when you turn the headlights on but does not vary in intensity when the brakes are pressed. any guidence would be greatly appreciated.

bad bulb driver side rear

bad bulb driver side rear

That was the first thing I had tried. It Turned out to be my turn signal switch. a few days later my signals stop working but would work in the defacto way that signals work when the switch has gone bad. it seems that the brake light/turn signal will illuminate when i have the turn signal pulled in some.

All power to the 2 main rear lamps (not including the high mount stop lamp) is routed through the multifunction switch in the column. Since the M/F switch is a common issue on these cars, it's ususally the culprit when problems arise if it's not something simple like a burnt bulb or corroded socket.