Discussion about the Korg PolySix synthesizer

Hi,

This is my first post. I want to make the step from monophonic to 
polyphonic and I'm now considering accquiring a Polysix.

I've spotted a Polysix from a seller but there's a minor problem with 
it. He explained to me (with his limited english...) that in polyphonic 
mode there's a "low sound" appearing with 4-5 seconds intervals as you 
play. He suspected that it might be LFO or VCA related, but wasn't sure.

This information pretty is pretty vague, I know, but I just thought I'd 
try this group anyway to see if this would ring any bells to anyone. 
Would anyone have any ideas what would be causing this?

Any help is highly appreciated.

/Einar