TM 9-2320-209-20-3-4 c. Replacement. FRAME 1 1. 2. 3. GO Put five wires (1) on HEATER switch (2) as tagged. Using screwdriver, screw in and tighten five screws (3). Take off tags. Turn around HEATER switch (2) and put toggle on HEATER switch through hole (4) in front cover (5). TO FRAME 2 23-99