Discussion about the Korg PolySix synthesizer

I think I've finally brought my P6 back from the grave after a big
KLM367 rewiring job, and it's sounding great!  I've followed the
calibration procedure, and it now seems to be 100% functional, except
for a complete lack of effects.  Chorus/phaser have no effect at all,
and when I select Ensemble I just hear a loud repeating thumping noise.

I've checked CN03 from the KLM367, and pins 4, 5 and 6 measure 4.8V
when the appropriate effect is selected, while CN03-7
(speed/intensity) swings from -4.8V to +4.8V, depending on the front
panel pot.  Other parts of the KLM368 (headphone & output amps) appear
to be fine.

Any help would be appreciated! 

Cheers
Frank