Hi Paul,
The local/program switch powers the spindle/coolant function with 5vdc and all switches must be connected together for it to work. When the switch is on local, it automatically supplies power to the spindle/coolant switches from the dyna 5vdc regulator. If the switch is on program, it needs 5vdc that no longer exists when the distribution board was removed.
The way I did this on my machine with the G540 conversion was installed a 48vdc relay that the G540 controls and then tapped into the existing Dyna 5vdc power supply to feed the relay (C/NO) that powers the local/program switch when in program. The AMC interface board controls the AMC spindle amp and needs a 5vdc signal to turn the spindle on. I forgot what color wire feeds the interface board but could easily find out with a meter. My dyna wires to the local/program switch are colored (brown & orange) with a red tag numbered (1&2). If you look inside your cabinet, the cable should be labeled as well. An easy way to find out is power up the machine and check for 5vdc on either wire inside the controller switch enclosure (brown/orange). So for example, say the orange wire has 5vdc, then the brown wire would need to be powered from the relay or vice versa for the program/G540 to work.
The coolant only works when the spindle is on. If you want the G540 to control the coolant, then another relay would be needed as well...
Attached are a few pictures of my conversion including a full enclosure that I built last year.
Good luck on your project!
Regards,
David