HI. I HAVE A RAYPAK RP2100 DIGITAL HEATER. THE CONTROL BOARD PART NUMBER IS 601588. IT WORKS FINE EXCEPT THE DISPLAY IS GOING BAD AND IS PRACTICALLY IMPOSSIBLE TO READ ANYMORE. CAN IT BE REPAIRED? APPROXIMATELY HOW MUCH WOULD IT COST? IF IT CANNOT BE REPAIRED DO YOU SELL REPLACEMENTS OR USED ONES? THANKS.