Basically, "you're hosed, buy a new system." Repair parts are hard, if not impossible, to come by for the older Jandy systems. You really don't need a completely new system. Jandy makes an upgrade kit that will convert your older system to an RS6 or RS8 for far less than the cost of completely new.

You get a new circuit board for outside and new control for the house. You will only need to use 4 of the wires that now enter the back of the existing panel as all of the signals on the new system will be digital.