I use Strip A Kit. You brush it on and let it sit for about 30 minutes, give it a light brushing with a tooth brush and rinse off. I strip and restore a lot of older kits. Some have two or three layers of brush paint. This stuff works every time and has never damaged the plastic. It is thick so you can spot strip small areas and repaint your mistakes.
I am not a shill for the company! This stuff is just plain good. You can get it from Hanger 3, POB 361 Arlee MT 59821-0361