I did finally find a video of a "wagon" bulb replacement. Unfortunately it is the left side he works on.

 

yeah so basically it means I can remove the bulbs without removing the assembly I think. So shall I just proceed by doing what was said but just removing bulbs like this?

thank you!

 

fontaine,as long as you can get to the bulbs, how you do it is not of concern. Get all the bulbs out and start putting them in one at a time. See what you come up with. Just make sure that you get them fully installed and not part way.

 

Ok so i've had all of the bulbs out, connected one by one. The bulb that I mentioned above (pointing to in pic) is the one that turns the 3rd brake light on.

I reinstalled all bulbs properly and even tried the problem bulb in 2 directions and still the brake lights are on. Even with the problem bulb out the rear left brake light is still on.

 

fontaine, sounds like you have a bad back plane to the brake lights. Do some looking in your local wrecking yards to see if you can get a new tail light housing. That is about the only way that I can see you fixing this.