OK lets go back to what you were told 19 years ago.
1. IF a jack(300 system) will NOT completely retract and its red light comes ON, you either manually lever it completely up or disconnect the 2 wire down switch at the top of the jack
2. IF it then retracts after you hit store and the red light goes out, you are good to go.
3. The CORRECT procedure for HWH 300 series jacks is to ALWAYS PUSH THE STORE BUTTON EVERY TIME YOU START THE CHASSIS ENGINE TO TRAVEL. This IS explained in the 300 series operators manual, NOT well explained, but it is stated to do this. This is because the TYPE system and down switches on the 300 series, Road heat and exhaust heat if close to a Hydraulic line will cause fluid expansion in the line and will partially extend the jack on that Hydraulic line. JUST ENOUGH TO EXTEND ABOUT 1/4 INCH AND CAUSE THE DOWN LIGHT FOR THAT JACK TO COME ON. By pushing store everytime you start the engine you put the system into hibernation(standby) and IF the heat expansion causes a jack to partial extend, the system will automatically engage store and the jack will retract and this happens BEFORE you get a red down light and alarm.
4. Now, IF you travel more than 30 minutes with a Red Down Light AND have the system in store and the down light stays ON, you will burn out the solenoid for THAT Jack. This is also true of the 600 series HWH jacks.
5. There is NO NEED for any type cooling of the system computer. ALL components are low dc amperage(no more than 15 amp in any circuit) EXCEPT the amperage needed for operating the Pump 12 volt motor. ALL circuits are fuse protected in your system UNLESS someone installed a larger ATC mini fuse in one of the fuses over the years.
6. IF NOT needed for a few months, I would send the defective control box to HWH for rebuild. This is cheaper but you have to wait for them to rebuild it.
7. Is your control box the one with the clear Plexiglas cover or the silver rectangular box? Your AP number IS the clear Plexiglas control box Doug