87 300SDL

Tach, idiot lights, blinker indicators all work, all outside lights and seemingly everything else works.

All auges (including electronic speedo) are non functional.
Illumination for dash and console all are non funcitonal (tested rheastat with ohmmeter and has almost no resistance when cranked up). I suspect some parallel between dead dash lights and dead gauges.

Ground locations behind dash look good and clean, fuses good, circuit board looks good and bulbs are good. (wouldnt a bad fuse take out the tach as well?)

while looking at the removed gauge cluster assembly from behind, there is a white 2 terminal plug socket on upper left. the plug going to it has been cobbled and butchered, has a green/yellow above a blk/purple (and another black/purple that appears to have been cut back??). I suspect a defective ground somewhere and/or this plug.

The round plug has had the center alignment key broken off but I can see the flat side well enough to line it up correctly and plug it in. I read somewhere that if someone opens up that round plug all the wires can fall out and be reinstalled incorrectly. Im not sure if this happened, I have no pin map or any way to tell.

PO stated that sometimes he would hit a bump and the speedo would work for a while.

I have searched and read extensivly and have found schematics for other models that dont coorelate with mine.

This car is going to have to serve as my daily driver starting next week as divorce and lack of work forced the sale of my 08 GTI. I could really use some help here, any wisdom at all. What can I try? any link to schematics or troubleshooting guides? Electricity is not my strong suit but I can get through the basics...with multi-meter in hand I await wisdom, links and/or experience. I know its long, Thanks for reading.

TIA,