have you contanced GW? they might have those and willing to share
visual inspection is actually first, any burnt marks or such, any ''fishy''
But, even without repair manual/schematics, it is highly possible to repair it, could be simple problem. i'd start with checking voltage lines and if you have ammeter (in-line) check if it takes excess amperage, and/or use bulb-trick (40-60w indascent light bulb in series with line, limits excess current, BUT it can effect power supply's normal operation) light bulb trick is handy too when replacing parts and powering unit back on.