Sometimes finding what's wrong with the makerbot is just a matter of knowing where to look. In this case the problem was between the keyboard and the chair.
Step 1, try a S3G file that I know worked in the past. Doing that I discovered that my print bed had gotten way out of level suddenly. Don't know how but the screw on the back right had almost fallen out. So I releveled the print bed and tried this S3G file again, this time watching the print carefully. And what to my eyes should appear, but the fact that I had built this file with the multiply plug-in on.
They say that the hardest part about making something fool proof is dealing with the ingenuity of fools.