I have the maintenance manual. Pin 1,2 and 14 Optional connection for X axis signal input. Disconnect the coaxial cable from the X axis BNC connector. Connect the center conductor of the coaxial cable to pin 1 and the shild to pins 2 and 4 (I think the 4 is a type, should be 14). Pin 3,15 and 16 Option connection for the Y axis signal input. Disconnect the coaxial cable from the Y axis BNC connector. Connect the center conductor of the coaxial cable to pin 15 and the shield to pins 3 and 16. Pin 4,5, and 17 Optional connector for the Z axis signal input. Disconnect the coaxial cable from the Z axis BNC connector. Connect the center conductor to pin 4 and the shild to pins 5 and 17. 6 NON-STORE is a function which is forced by grounding pin 6 to pin 19 (except when using the TEST SPIRAL switch). 7 ERASE INTERVAL is a signal output that goes from +10V to +0.3V during the interval of erasure. 8 WRITE THRU is accomplished by grounding pin 8 to pin 19 and exciting the Z axis. 18 ERASE FUNCTION is obtained by grounding pin 18 to pin 19. 19 PROGRAM GND is the ground reference for remotely connected external functions. 20 VIEW MODE is a function that is forced to exist as long as pin 20 is grounded to pin 19.