Dave, I think I gave you bad instructions on #1. If you have the original regulator the voltage will vary like you have seen. Sorry, I was thinking about the replacement that is fixed at 5v. My mistake.
It looks like the voltage regulator is at least cycling and maybe working correctly.
Try step 2. If you ground each of the sensor wires the gauges shoul each go full scale.
Sorry for the lack of precision in the instructions. This kind of stuff is confusing in person, much more from a distance.
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