91 honda accord central locking not working?

My 91 honda accord LX sedan (USA) will not lock or unlock any of the four doors with the central locking. When I use the door lock switches on either front door I can hear the relays cycle in the module inside the drivers door and I can read the power with a test light at both front servos but none of the servos operate? Can anyone help?

FYI - It does not have remote locking only central.

Any help is much appreciated