The 6700 "reads" the plate and will not allow any but straight stitches when the SS plate is on. And when the left hole ss plate is on the machine only allows SS in the left position.
"Inge, there is a very easy fix for "eating fabric". Get a straight stitch
plate and use leader/enders. Don't forget to put a sticky note or
something to remind you not to use zig zag/decorative stitches when
using the straight stitch plate"