Use plain bleach,very little water,and 5-6 hours to soak completely.It will not harm the logo.I did this to my white pc-engine to restore it to whit eagain,and now its completely white.Just to save the idiots ou tthere,too,just soak the plastic shell,take the system apart,and take everything out,soak the shell,when done dry it out completely,and use a air can to get droplets out of it,and out of the systems cd drive lids top spinner mag clamp,otherwise youll have bleach water droplets flying around your cd-drive,and posibbly ruining it.Good luck!!!