Against my hopes and parayers, sporadic blanking of the GPI display has failed to correct itself. Following RBM's advice, I tweaked the ground receptacle on the harness side of the 4-pin connector. No difference. Readings taken from the switch side of the connector while in 3rd and 5th gear indicate no problem there. I removed the instrument pod and cleaned the multi-pin connectors, then I partially disassembled the pod to check on the pins of the GPI board. During my visual inspection, they gleamed at me with shiny nickel-chrome cleanliness so I decided I could only make things worse by getting at them and I retreated. Now the GPI display does not even flicker -- it is off all the time. I doubt I broke anything. I only sprayed Deoxit into the female side of the main plugs.
I looked again at the 4-pin connector. On the harness side (female), with the ignition switch on, I get continuity and 11.45 volts between the brown ground wire and any of the other three sockets. However, shorting them jointly and severally with the ground has no result on the display.
Do I need to overcome trepidation and get at the shiny pins on the GPI board? Is it possible I dropped my chewing gum into the female side of the main connectors? Any ideas?