I've been having a couple of issues with my Summa S2 lately. Using Onyx 21, but it won't read the barcode anymore. Also, using go sign from Asanti, it sometimes adds extra marks in the registration, that aren't printed. I've trouble shooted by deleting those extra marks in the back end. It will read vertically, then go across the sheet and not be able to read the back mark, even though it's right over it. So the plotter prompts me to set the tool over the mark it can't read. I do so, it continues as normal, but starts cutting off.. horizontally off though.
I think there is something weird with new summa upgrades. I haven't upgraded recently, because I have a colleague who has had other, separate weird issues. Which he eventually pinpointed on a software upgrade with summa.