I would start off diluting the APC try 4:1 first, if after a light agitation you feel you need more strength then step it up 2:1 until it gets the job done with gentile agitation. I would take the time to cover as much exposed electrical prior to doing this as well as watch a few videos on the subject just to feel comfortable doing this.
use distiled water for your dilution if you can.
good luck post some before and afters this will be a test of the best APC on the market.