Discussion about the Korg PolySix synthesizer

Hey guys been having issues with voice #6. I spent last few hours adjusting all voices to the same level and retuned all of them, even adjusted the Reso on a few of the voices aswell. But the 6th voice is the issue and I'll play a saw wave and all 5 voices sound exactly alike but when I hit the 6th voice it is the same volume and in time but just sounds a bit off like almost out of phase or something. It's very strange. It's hardly noticeable but now that I'm aware of it I must fix it. Please help:(