If it absolutely, positively has to be degreased, Trichloroethylene (TCE) should be considered as an option. Many industries involved in painting sheet metal prep the metal prior to painting since paint will not adhere to surfaces that have cutting oil residues remaining. Wear rubber gloves as there is an exposure scenario via dermal contact i.e. the stuff will degrease humans. Apply in very small amounts with a Q-tip. Should be available in a small can at your local gun shop in the cleaning department.
David Allen
Marietta, Georgia