Hi. As John mentioned in another thread recently, try using a suspect painted repro as a 'pencil' and 'drawing' with it across a piece of paper - if it's painted it should leave behind a residue. If it's plastic it'll just leave an indent. Put up a picture if still unsure and we'll take a look.
thevintagetoyadvertiser.org 1970s and 80s vintage toy ads and other retro paperworks
imperialgunnery.com Vintage Star Wars action figure weapons and accessories guide