Cluster gauges jumping!

[PeytonM]

1989 Mooney 201. 28V. My airplane was in for new audio panel, Aspen PFD, ES upgrade on my Garmin 330, new Hobbs meter, standby vac AI. First flight: R Fuel, Fuel Pressure, and Oil Pressure needles were bouncing around on TO power, other 3 gauges (L Fuel, Oil Temp, CHT) were solid...bizarre! In cruise, things settled down, although R Fuel still bounces around occasionally. These are the factory gauges; not Moritz gauges.

Although they were not touched, we've checked grounds. Although they looked good, we cleaned anyway. (If ground was bad, I'd expect all 6 gauges would exhibit same behavior, I think.) I've thought about engine vibration, but I'd expect to see all needles bouncing. Like I said, it's only 3 of the 6 gauges. And this is new observation since panel work. Tried with Aspen off, no diff.

trim.7F40D22B-9519-4E85-8D76-50670E5D7E70.MOV

[Bob - S50]

So what do those three gauges have in common that they do not share with the other three gauges?  I'd start there.

 

Bob