electrical guru what should i be looking for tail light problem

Yote said
Since the brake and turn are the same in the two filament bulb and your tail light works I would suspect a bad bulb. I believe it would be an 1157. If not that check your contacts to the bulb.
Yote

replaced the bulb numerous times with bulbs known to work, tried new socket even did a test before the rear harness same problem.