I use the granular Spic and Span. Then wash the parts off with the hotest water from the tap. Blow off with compressed air and the spray with WD40 and let dry on a paper towel. Then wipe off again before reassembly. It is important not to let the metal parts in the ultrasonic rub on the walls or touch on other metal parts. I have devised a couple of baskets , made of plastic from raspberry sales at the grocery. Then separate parts with a piece of wood shingle or similar. It will clean up what days or weeks of solvent could not do.
