Do you have the maintenance manual? The TNC turns the KTK on by relays, including ready as well as forward and reverse. First I would see the state of these relays.
Next, is the LED ON on the MTI-1 board. This provides the field voltage to the spindle motor. Lastly, the KTK has a pile of LEDs on the main borad for diagnostics.
Ther is no support, no parts, no repairs available from KTK. These are considered obsolete.
EMI has a substitute drive.