Regular scented dishwashing detergent bath is safest for plastic
pieces and makes a good bath for everything.
Citrus cleaners will work faster but may be too harsh. I use a
variety of acid brushes cut down and soft tooth brushes and paint
brushes. I learned all about it with inside telephone systems. I
have had to throw away some mics after immersion.

VFO230 will have fragile plastic, encoder and markings, so very weak
solutions there. Housing should be dipped in a stronger solution and
brushed. Boards will be a problem as anything you do will wash
debris under the chips causing shorts between pins. If you do dip
the boards, it is risky but use clean de-ionized water in the final
rinse.