Ted, this probably isn’t the best way but works well for the typical PE or brass part:
I like to use AK or Mig Burnishing fluid to blacken metal detail part. Then if the paint chips or flakes later there isn’t any shiny brass exposed. There also a prep chemical for painting metal parts but I rarely use it. Still using Floquil from the days of old and it seldom has any adhesion issues to the burnished PE or brass.
On a similar note, someone asked recently about how to help paint adhere to PE. You don’t neep special primer, and to clean it you can use vineger, if anything. But why?? I lightly sand the surface of the whole fret (only if it’s begun to tarnish) until it’s shiny. That also puts micro scratches on the brass for paint to adhere to. I’ve never had an instance of paint flaking off of brass parts.
I’ve done a good bit of keyboard bashing before I put this query to the hive. Results nearly always came back for metal colored paints. SO, PEBKAC seemed an over-simplification. LOLZ
I used to be a software troubleshooter for a chemical company (we had some water analysis program for Windows) and also did general IT duties and that was a common diagnosis of the PCs in the sales rep department.
It’s a combination of some collecting my wife and I do. She collects Pez, and I collect Brekina HO scale vehicles, specifically their VW buses. They are a German company.