Mellotronists

Hi:

I have been recording a song with 6 mellotron violin tracks (three
pairs of mellotron-violins so I can sustain a note on some parts). The
final result is that I get a very audible flanger effect on some parts
that weren't intended to be there. I am using very little effect, just
some very LIGHT reverb from a "Holy grail" reverb pedal I use with
guitars, organs, flute etc with very nice results. 

Im using a Yamaha AW16G for recording the tracks. You can hear it in
www.myspace.com/ignacioNieto (it's called "la muerte de la
inocencia"). Any idea of how can I get rid of that flanger effect?

Thanks.

Nacho.