Originally Posted by Zephod_beeblebrox2
. . . Clearly the problem is wherever the connection to the engine is located. I have yet to find that.
In some of the skoolie supplier links others have posted, elsewhere on those sites I have seen rebuilt International gauge assembly circuit boards listed. If they are selling them, there must be a market for them.
I suspect the trouble is closer to the steering wheel as icnivad has found. The dash circuit boards may be a known weakness. You may be able to fix a bad ground or solder a wire across a crack in a wiring trace. If not, you may be able to order a new board and mount it to your panel.