Discussion about the Korg PolySix synthesizer

After -one!- Year i\ufffdve got a replacement KLM-367A, which had also two 
defect 74LS08, but it was no problem to repair. Then the effect Unit was 
defect, replaced it also.

Now my Poly works, except the Voices are detuned. I give you an example:

www.phasereffect.com/pub/poly6.mp3

Can anyone tell me how to correct this?

Greetings

Stef