Redoing putty after painting

Yes you can,it sucks because your basically going back to the beginning,but if your not happy, a do over is possible.But just on the area in question, not thr whole model.

Hey, Bright. You can certainly sand down the offending spot, but if you already painted over it, you may find you will be sanding for a long time using super fine paper. More likely, you'll want to use a coarser grit to work through the paint and then a finer grit to smooth out the putty. Your biggest problem will be making sure you don't have any edges left on the paint you sanded through. If you do, those will show up when you repaint. So make sure you feather the edges of the paint you are leaving on so it transitions smoothly onto the exposed plastic/putty.

Ok, great, thanks guys. Since this was my first post it took forever, so I went ahead and tried it. It came out all right, I think I used too coarse of a grit in one place, and now it looks scratched. Oh well, learn something new every time.

I frequently use multiple layers I find filer-paint-filler-paint, etc. I have had no problem with either sticking to the other.  I figure that is just the nature of filling seams.  One of the reasons for primer is that it can show up such imperfections in your seam filling before you go to color paint.

Use a very fine sandpaper or Mr. Clean cleaning pad to remove scratches and spray paints.  I've done this numerous times before.  But nowadays I don't bother with some scratches.  Most military machines are dirty and full of scratches.  

Use black primer because in a good light setting you can se the flaws that modelers often miss.Semi gloss will work well.A small flashlight helps you see all the areas that need to be re done.The priming stage is the best time for this .Also it is safe to sand primer.It may take many hrs or days to get good results.