I've had a few different models, they all seem to either have the "jump around" effect, where the needle just goes haywire, or it sticks and does nothing,until I try harmonics, low notes, high notes..or turn the power off and on,then finally tunes. All the cheaper korg stuff seem to,I need an output for my effects loop, and I'm willing to spend. Are they all so unpredictable? Or have I bought so-so stuff? It's embarrassing in pro situations when I take too long to tune. Does anyone know what I mean? Or perhaps I have lousy tuning technique or bad batteries?.. I dunno.