I’m in interesting situation
901A+901B+901B tracking is well for 5 octaves
third 901B is out of scale (about semitone difference in 2 octaves). Are there any internal trimmers to adjust scale parameter for 901B?
No scale in the meaning of ocatve spreading in the 901B. Did you follow the 901B adjustment procedure of the service manual? When I cloned the 901A and B I faced side effects of the VERNIER control meaning changing the VERNIER also changed the scale a little bit, so perhaps you could try to track the oscillators with exactly the same VERNIER positions using the tracking trimmer instead of following the service manual adjustment procedure.
See also http://www.analog-monster.de/mmt901_en.html
Best
Carsten