Even acetone free nail varnish remover can damage the plastic as I once discovered.

You could try dettol (make sure its got Chloroxylenol in it). Its what I use to remove paint/varnish from models. Mix it about 50/50 with warm water. Submerge the part, leave it for 12-24 hours. The only down side to this is Dettol has a very strong smell.