REMOVING THE OLD center triangle started off easy enough, even though it would only peel off in incremental pieces rather than peeling off cleanly in once piece. However, somewhere a bit past the point of no return, the remaining portion of the spot got increasingly stubborn to remove. I wetted the area and gently, but firmly worked at it with a fingernail (and finally removed it entirely with a bit of help from some Acetone), but it took nearly fifteen minutes to work the old spot off the mirror. I at first thought the only very minor-looking scuffs I'd caused would be covered by the new spot, but this didn't turn out to be quite so. The problem is that even though they're confined to the immediate vicinity of the triangle, they degrade the clarity of seeng the points relative to the circumscribing circle in the Catseye cheshire, and the clarity of reflections of P1, P2, and P3 in the autocollimator. Though hardly prohibitive, they are a big annoyance to the Catseye collimation process, even while being a helpful boon to the Glatter collimation process (especially secondary position) switching to the perforated center-spot was intended to provide.
ANYHOW, the moral here is that removing an old center-spot is not as riskless a procedure as some prior threads have made it out to be, particularly with regard to the supposed safety of any nicks to the coating being confined to the secondary shadow. True, but beside the point for how nicks may interact with collimation accuracy. Also, as the photo shows, the nicks (which seem very minor at the time while working off the old center spot) can wind up being more substantially visible under collimation lighting conditions than you may at first assume (at least until you see them in very bright light as needed to take this picture).