Have you tried changing the needle? Maybe it got a bit bent. I had the same problem a while ago. I have a Viking Rose. I had been sewing some badges onto towels for a friend & thought I had really messed up my machine when the needle started hitting the metal plate. However I just used it today & it's running smoothly again. I still had a problem with the walking foot & the needle hitting the plate when I used my favorite stitch #17, so I purchased a new waking foot. I figured I wore the one from 1996 out.