PCB solder joints blackening after two week's use - pic attached

[chrisb]

I've had reasonable success cleaning boards prior to reworking with a commercial spray flux remover and short bristle brush (similar to tooth brush), followed by rinse with isopropyl alcohol. (then an internal rinse with ethanol )

Careful with solderwick to clean/scrub excess solder and flux residue from eyelets - George's boards have quality plating, but not all can stand the prolonged heat from this process. I've had to patch over several foil lifts while working on mods to an old Jolida amp, but had to scrape like crazy to break the trace on George's SimplePP board to mod for series choke in power supply.