1.   If none of these works, sand the finish and apply two coats of a latex house paint.

2.   If there are two coats on, sand the finish and apply a latex enamel undercoater, then two coats of a flat latex wall paint.

3.   Sand the finish thoroughly with medium sandpaper, to roughen the enamel and reduce gloss.

4.   Sand the finish to remove those rust spots, but you do not have to take off all the latex undercoater.

5.   The solution there is to sand the finish lightly to reduce gloss and roughen it so the final finish will adhere.