Sequential circuits samplers

I wanted to throw this question out here one more time...  

My filters need calibrating, but for now I can live with it... it adds a little variation.  

But also, it seems 4 voices are slightly quieter than the others...  This might or might not be linked to the filter frequency, but it seems more of a "loudness" issue. 

There are no trimmers inside so I assume any calibration must be software based. 

Does anyone know if/how this can be done??  Does anyone here actually have the technical manual who can share this info (if it even exists?)  I can't imagine there is NO way to calibrate these things.  

Thanks!