Did GW eliminate the drop down box in the cabin, mentioned above? My 2000 has it, and I changed a tach last week-end with no problem. Your spinning screws may be going into something like the silver thing you see above and below the gauges. You are looking out the lower E-box at the steering wheel.
Try Super glueing one of those Phillips head bits into the screw head, and pull as you try to back it out.
I have all of the wires from the upper box, and the fuse panel below the helm, and the cable chase from the hardtop feeding into that space. Can’t imagine having to access it through that small panel.