Just as a side thought, are the PCB's on the RC-20XL, double sided, or maybe 4 layer, if the latter, this might not be so easy to repair.
When I read his problem description I asked myself, why does he sell it as broken when he says it is so easy to fix. After all he'd taken the effort to pick it apart and the soldering bit should be easy and if he fixed it, he would get much more for it than selling it broken.
I think you already mentioned why he didn't fix it himself. Wonder how much Roland would charge for a replacement board?