I just had a battery experience with my Quickie/PJCCS.
I had been listening reasonably regularly, and had been noticing more noise than usual, more microphonics. I thought the tubes were going off perhaps. So one evening I decide to try some new-to-me tubes in the Quickie.
When I powered back up there was a fairly loud hum/buzz in both channels. I thought I'd busted it. Looked around, found one fragile joint and resoldered. No difference.
I finally got around to measuring voltages - none was right. So I checked the batteries - of the four Energizer 9v two were around 2.3v and the other two were negative values. Today I popped in a new set of 9v (the D cells were 1.4v so I left them) and the voltages are all good again. Fired up the amps and it's totally back to normal.
Whew.