I am not the worlds greatest model painter, I assume you have something like a Tamiya magnifyer? when I have to paint within a painted area I paint around the position with a small brush using a light oil I then paint the desired subject, when it has dried I then carefully remove the oil smear which takes any over painting with it, just a thought. shaun
Doc if you go to Tamiya's site you will find their magnifyer which is a spectacle like frame with a hinged front and in the cloth wallet are 3 separate pairs of different strength lenses these clip into the hinged front and it really is a great way of seeing things in close up with your hands free to paint or whatever, you know when you buy something and within days you wonder how you managed without, you know like a wife or a decent screwdriver,( please I pray she never reads this) http://www.tamiya-model.co.uk/shop/tami ... 14200.html.
shaun