"Are you and Steve claiming that there is a cause for the specific new order of bases after the miscopying?"

Why not? There would be a cause for the initial impetus to change and a cause for the particular way of recombining. The specific new order of bases you refer to will almost certainly be completely useless, remember. There will be millions (I'm guessing) of duff, or worse than duff, mutations for every potentially-useful one. There's nothing intelligent going on.