Before you blame the ballast, you might want to check the wiring, switch & end caps. It is more likely that corrosion had caused a fault in the wiring. A good ballast should last more than 3 or 4 years.
You prob can't find a suitable ballast at the hardware store. What you need is an electronic load sensing ballast of at least 110W. <2x 55 usu. have 130W ballasts, so you can interchange the 55 & 65 bulbs.> You might be able to find electronic ballasts for T8 shop lights of 64 W or so. 2 of those might work. <There is no guarantee that the cheap shoplight ballasts will be load sensing, but 65W ballasts should drive the 55W PC
.... YMMV> Your best bet to find a good ballast is at a specialized lighting store or on line.