Step 1: Strip machine heads and remove all covers. Blow out dust and clean thoroughly.
Step 2: Inspect all head bearings, color change cam, color change potentiometer, color change motor, set color change flat spot/needle center, needle bar reciprocators, set head timing, synchronize multiheads, check jump, wiper, picker and trimmer mechanisms.
Step 3: Remove all grease covers, remove all grease, inspect moving parts and re-grease
Step 4: Inspect all electrical connections, remove and re-seat all circuit boards.
Step 5: Replace heads, check needle centering and head alignment.