2003 Cobra - Sequential Tail Light Problem [Video]

Got my car inspected today and failed because my tail lights aren't working properly. I installed a sequential kit many many years ago. Worked fine for years and then started acting weird. I never bother fixing them but today the car wouldn't pass inspection. The guy said they needed to work the same way...even though they passed the car last year with the same issue.

Anywho, the passenger side works fine. It's the drivers side that has the problem.

When I turn on my hazards, ONLY the middle bulb is out. However, I checked the voltage and it is getting voltage. So I'm not sure why the bulb won't light up.

When I use the left blinker, ONLY the bulb closest to my license plate blinks, and it does it rapidly (I assume because the other bulbs aren't lighting).

All of the bulbs are good, I checked.

Nothing lights up, on the driver side, when I hit the brakes. Unfortunately, I don't know if this was the case before I started checking everything or if I got it back from the inspection place like this (I doubt it).

Below is a video to show the issue. Also, you will notice that sometimes when I insert the bulb it will light VERY briefly. But that doesn't happen every time.

Maybe the bulbs are not making good contact with the socket??

Any ideas on what to check or how to fix this? Thank you.