Vintage Synth Repair

Hi folks,

I've had this funny problem with my A-100 that I just can't get rid of.  When I turn the organ 
on, as soon as the Leslie warms up, I hear a sound as if low notes were stick.  Then, I turn 
the vibrato/chorus selector about 2 full clockwise turns and the noise disappear.  When I 
select either Vibrato I, II or III the sound is chopping but if I select the Chorus I, II or III it 
sounds fine.  I've rebuilt the Scanner Vibrato twice without luck.

Does anyone can help me?

Alex