69 Dart Brake Light Problem

I have a brake light problem in that the turning signals work all the time but if i move the turning signal lever a little up or down while in the center postion the driver's side brake light will not work. I am replacing the turning signal cam this weekend if NAPA got me the right part. I ordered it but did not know the part # to give to NAPA.

Long story short I know the brake light power feeds thorugh the turning signal swith.