Korg Poly800/EX800 Users

I just got a Sega 9v PS as sugested in a previous post.  When i plug
it in though the unit will not turn on.  Even when there is no A/C
going to the P/S the POLY will not turn on even with batteries 6
C-cells installed.  As soon as i unplug the 9volt DC line it will
power up.  I get the impression that this might also be related to the
fact that the headphone out does not work as well (line outs work
fine).  Is this an easy fix or should I just put in a DTDP switch to
go from batteries to DC in?

Thanks.