Question about tuning the Prophet 6
I recently got a used Prophet 6 that as far I can tell is in great condition. I pretty quickly noticed that some of the presets that are saved are very out of tune, some of them as much as 30 cents. It's not intentionally detuned oscillators as far as I can tell because both oscillators are equally out of tune with a tuner. And it's not even preset, so I can't fix it with the Global Master Tune. I thought maybe the previous owner had intentionally done this with certain presets somehow so I've been creating sounds from scratch and saving them as presets. But now I'm finding even two different presets that I've made from scratch can be wildly out of tune with each other.
Is there something wrong with this synth, or is this expected behaviour? Is there a way to tune individual presets? Am I missing something that could be causing this? Help!
Edit: I have run the calibration process (Preset + 0) multiple times and it doesn't solve the issue either.