Yes, I have seen this version but not the problem you describe.
Of course, if the tension of the graphite brushes is too strong, it will cause increased mechanical resistance and slow down the motor.
The majority of repairs to the MST involve disassembling the motor to clean and polish the rotor and redress the rotor brushes along with faulty switches.
Hi! the graphite brushes are not too strong, i adjusted them only to put a slightly pressure and the motor work.
The motor is working but i dont get the sync light on and by my calculations is running at 27 fps.
Do you know more about this version of motor to tell me? the modern MST makes much more sense interpreting the circuit. This model, first, i dont have the schematic, second, is too much minimalistic to my taste, seems to envolve non-electronical solutions (the graphite brushes)
Since i once in a lifetime was a electronics technician, i have the skills to build one crystal sync regulator starting from a project or circuit. Maybe with effort i can develop my own project but is been too much for my time and my severe pain (early rheumatism). Maybe someone can sell me or show me an scheme like this so i can adapt to the MST or an stepper motor perhaps.
In brazil we have criminal taxes in customs so, buying an new Tobin Motor is practically impossible (i'm a student and my income come from fixing guitars and guitar tube amps). My next project will be an 16mm frame by frame telecine unit with some hi quality HDMI camera. I have one of those super8 with an super webcam installed and works like a charm, i'm able to capture 1600x1200 video from it.
Thank you all in advance!
a hug from Brazil