I noticed on yesterday's flights my ammeter needle was dancing back and forth around the "zero" top position. Very small amplitudes on either side of the zero top center. Also the digital voltage indications on the Davtron 655 was jumping back and forth 13.8 and 13.7 V. I didn't think much of it as I was setting up for an approach. Didn't check the EDM800. I had the master switch replaced last annual and I still have to check the connectors in the back to be sure they're nice and tight.