I just wrap the board and connector ends in plastic bags and seal them off with rubber bands, etc. Then fill yr sink with hot soapy water, and dangle the coiled cable into the water, let it soak in the suds. After a good soak, take a wash cloth and gently rub along the cable with more warm sudsy water, rubbing off any stubborn crud. Rinse and repeat.
Easier method: order a replacement cable and be done with it.
You're welcome.