Do you work with Ian as it was Ian who was asking the questions re the model. As you can see by the history of this problem we are not really getting anywhere but Ian seemed to know about Hot Tubs if you are more of an expert then by all means have a try.
Quite happy for you to take over we need to resolve the problem as quickly as possible.
Keith ~ herewith a link to the user handbook for your 9000 series hot tub, page 5 refers to the reset procedure for the pressure switch. Personally, I would exhaust all avenues prior to replacing the pcb as the FLC refers specifically to a pressure switch fault rather than a pcb error. So check the wiring between the pcb and pressure switch and then check (using the link information) that the pressure switch is actually working/not working/needs adjustment. Note the remark about the heater not working until the FLC code has been rectified ~ good luck. Ian
~~ http://www.hydroquip.com/Owners%20Manuals/SOLID%20STATE/9700/Troubleshooting_Guide.pdf ~~