Wash the part with Dawn Dish soap. Blow it off with an air hose, then wash with Alcohol and water 50/50. Then wipe with clean cloth.
Lacquer thinner or acetone evaporates too quickly and you don't have time to wipe off the oils. They dilute the oil, then evaporate out and leaves the oil behind. The alcohol/water, dilutes the oil and holds it until you can wipe it off with a clean rag.
Frank
