If all other methods for moving the ADC fail, there is a last ditch procedure to attempt to move the prism cells into the Null position. There is a Bypass Mode Switch that is also mounted on the front panel of the electronics box (see picutre below). .
Figure 1: ADC electronics rack.

Bypass procedure

1. Find the ADC electronics box located in the HIRES electronics vault.
2. Bypass Mode Switch is mounted on the front panel of the electronics box.
3. step 3
4. step 4

The adc electronics box is located in the HIRES valut.

Please see EL-3612:6 "Interlock wiring, bypass and emergency stop wiring details" in the electronics manual for more documentation about the bypass switch.