Ok managed to get a few existing scans to work . Black background and 600dpi . Now the strange part is the 3 cent small queen came out with perf 13.5x 13.25 or vise versa. I don't have my unitrade handy (packed away for holidays in shame) but I don't recall a perf 13+ on a 3cent small queen. I also double checked with a photoshop gauge and same results. Even stranger is this is the 3 center I posted awhile back that was so oxidized it looked black. Now I'm really curious-- Thanks PERFOMASTER 3000
EDIT


Rescanned at 600x600 and re did with both computer perf gauges with a result of 12.25x 12.25 which is still interesting. Problem with previous pic was it was read as 600dpi but the actual image was shrunk within constraints. So as long as your scans are done properly and not optimized or shrunk (can be cropped without effecting DPI) everything works great.