I have two P-07's and one is maybe a bit easier than the other due to differences in tolerances and fitment, but they both require a significant amount of force, and usually I use the corner of a magazine base pad or some other non-marring pointy tool to apply that force. If I could just force it out with my finger I might be concerned about it. As far as lining up the marks on the slide and frame, I always do it on both pistols when removing the slide stop, but I have noticed one goes back in more easily without lining up the marks.