Its hard but try to remove all of the trim from the top side without taking the section out of the mold cavities. This freshly shot plastic is loaded with surface tension the makes the stuff almost sticky. If the pieces are removed, the surface tension is gone when they get replaced. Put each piece that gets taken out of a cavity in the exact same cavity and pay particular attention that it goes in with the sprue end forward. I know, it sounds putzy, but the more practiced you get at developing a work pattern the less likely you'll find those over shots. The slow injection is a very key part in this. Takes practice.
Like many other aspects of learning the ins and outs of this stuff, I suggest you use some junk plastic and practice this process so good plastic doesn't add to the junk pile.
