Discussion about the Korg PolySix synthesizer

Hello group.
I'm having problems with a poly 61.
I know this is a Polysix group but... maybe someone can help me.
The problem is that DCO1 produces very low sound when sawtooth wave is 
selected and barely no sound when one of the other two waves are 
selected.
DCO2 works fine as all the remaining functions.
Any sugestions?
Thanks in advance!
Best regards.
José.
Portugal