Loose needle plate on Pfaff classic quilt

Question

I had a hunk of fabric pulled down into the bobbin case. I pulled it out, replaced the needle and tried to re-set the needle plate. It sticks down just fine on the left side. It does not stay down on the right side. Now when I sew, it rattles (I miss my hummmm). I replaced the needle and the bobbin. I have taken that plate on and off six times, same result. Is my feed dog out of alignment? It seems like this happened one before and it was something so simple...