I have had good luck with ppg acryliclean. It is a mild wax and grease remover. Before i apply it i make sure all the heavy build up is removed by wiping motors down with a rag. After that i just simply fill up my hvlp gun and spray away! I use this same method every time i complete any work on a concours quality restoration also. Never hurts to hit the shiny spots with some good chrome polish after you've acrylicleaned the whole compartment.