I was just tuning my new uke, and as I've said, I'm not really used to friction tuners. I clipped on the tuner, fired it up, and plucked the G string. It was a bit flat, but that's to be expected.
I grab the tuner knob and, as I've been advised, tried to "pinch" it, rather that twist. I tried for as little input as possible. I plucked the string again; still flat. So, I "pinched" a bit harder, and felt the tuner move a teeny bit. Still flat. I did this several times.
Until I realized I was plucking the C string, not the G. I was turning the correct tuner, but plucking the wrong string. What an idiot. I'm surprised I didn't break the G string by stretching it too tightly.
Oh, well, no harm done (except to my ego)....