Hi Gary. I had a similar problem with the mirror I'm making. I was told by my local ATM club that I could go ahead and figure the mirror because the stroke that I would use would eliminate the problem. I decided to fix the problem instead. I did 1/3 strokes centre on centre. Rotating the mirror and walking around as I went along. This eliminated the turned down edge that you have. I did about 15 minutes at a time and retested. This may increase the size of the hill at the centre, but this is easy to remove." Let the mirror overhang the tool and work the centre portion of the mirror near the edge of the tool". ONLY DO THIS ONCE OR TWICE before rotating as you may end up with a hole in the centre and this is harder to remove. You could try larger strokes with larger sideway movement if you are not game enough to try the first method. Remember to cold press the mirror and the lap before doing any more strokes. Overall it looks pretty good. I suggest you buy a copy of texereux it will help you greatly an consider joining
http://www.atmlist.net/mailman/listinfo.cgi/atm. These guys will help you out. They have helped me. If you want to figure the mirror instesd let me know and I will show you the stroke that I have used on a previous mirror.
Regards Cristian