My machine started squeaking, so I dropped a couple drops of oil on the rod that goes up and down whilst sewing. Now all my stitches are grey/black now. My LQS said to just sew on scraps till it stops........any ideas on how to speed this process up? I've switched to cotton thread, thinking it would absorb more, but it's STILL grayish/back. Just wondering what others do when this happens. Thanks for comments!