I use a plastic putty knife because it has a wide flat surface. Don't worry, you're not going to pry with it.
Tape the tip of the blade flat to the brass plate with duct tape or masking tape. At the edge of the plate, on the body, place a cloth or folded-over paper towel for protection, and something flat (I use a carpenter's pencil because they're flat, so they don't roll away when you set them down) to use as a fulcrum.
Just a slight nudge downward on the handle of the putty knife is all it takes. You can even twist the handle sideways if you need to, as long as you don't let the fulcrum slide around. Cleanup any tape residue with a dab of rubbing alcohol on a paper towel.