I'm working on swapping a CPR playfield into my game and wonder if someone could help me out. My playfield is only drilled for 3 posts behind the 4-6 targets but I see most originals and some CPRs drilled for 4. My original has 4 there. Anyone know for sure if 3 or 4 were originally used? I can see why you might want a fourth there to shape the rubber and perhaps avoid a ball trap situation under that lower right pop. The area on the playfield does have a slight shape to it.