Mellotronists

So, has anyone kept a record of how badly the M400 Three Violins are out 
of tune with each other and which keys are the worst offenders?  I've 
got 1407 back together and playing and I'm down to minute keyboard 
adjustments and I'm wondering if there are certain notes that I just 
shouldn't attempt to put that much time into.  Most notes sound OK as 
you're running up or down the keyboard, but if I try playing something 
in unison an octave apart or certain chords, it becomes obvious there 
are still some tuning problems. As my pinch rollers are finally spinning 
like they have ball bearings, I guess I should  check motor stability 
and the SMS4 to make sure that issues aren't originating there.

john