Searched, did not find what I need...

95 Disco I
Have Jump Seats (relevant to those who suggest I tear out panels to find wiring. I am willing, but not looking forward to it...)

Issue:
Intermittant L & R brake light function

Symptom:
L&R brake lights wll function only occasionally. On start up, I have wife apply brakes, and I SLAM rear door till lights decide to come on. Usually by third try.
Third brake always functions.
No other elec issues (beside inop cruise, since I purchased)
Running lights work OK

Had drivers side bulb go intermittant first, now both.

Solutions?
Obvious that an open has developed in system. I am assuming switch is good, as 3rd light works.
1) where is the ground for these lights, and is it shared with third brake light in door? If shared, kinda eliminates ground. Please be specific.
2) Is there a relay, that when I SLAM the back door, is getting enough of a shock.
3) Anyone know which fuse this is? I will replace.
4) I'm guessing that using my rear fogs as a manually operated brake light system is just surrendering to "Lucas, Prince of Darkness"?

Heaven:
French Food
English Police
German Cars

Hell:
English Food
French Cars
German Police

Thanks in Advance...