These aren’t necessarily interchangeable with the MM-1000, but may help explain the underlying servo architecture.
- Ampex MM-1100 Operation and Maintenance Manual
Includes capstan servo schematics, tachometer feedback, reference oscillator, speed selection and test-point information. - Ampex AG-440B/AG-445B Capstan Servo Kit manual
This documents external reference frequency input and variable-speed operation. It may be useful for understanding how Ampex implemented external control of a DC servo, although we shouldn’t assume the connections or circuitry are identical to the MM-1000