PDF issue resolved
So, in case anyone else runs across this problem, here's a solution.
When 'printing' your tax forms in web TurboTax, you get a pop-up window to view the PDF file using the Safari plug-in (which was intially Preview, as I had never installed Adobe Reader previously). I saved the PDF from this pop-up window. The PDF looked fine in preview, but was missing the right edge when printed, or when viewed in Adobe Reader.
I installed Adobe reader and it's Safari plug-in, and re-generated the PDFs from TurboTax. (That is, the PDF processing in Safari was handled by Adobe, not Preview.) Now, they are identical when viewed in Preview, Adobe, or printed.
Implies that the issue was related to Preview? 😕