I've recently got hold of a peach rubik's cube, which has some interchangeable pices (corners and edges as far as I can make out), and also some edged whch seem to be reversable. Whatever I do, I seem to end up with one face 90 degrees out. It's new, and hasn't been taken apart, so I assume I'm going wrong somewhere with one of the interchangeable pieces, but I can't figure out what.
This is the first cube I've attempted in a a very long time, and what little I ever knew about them or the theory behind them I've forgotten, so I'm hoping someone could suggest where I might need to look to solve it. Would swapping corners make a difference to the orientation of a single centre? Or is that not possible?