I am a sad, sad girl today. My beloved Singer 403A Slant-O-Matic is not doing well. She's sluggish and sometimes just won't go at all. The light goes on and the foot peddle seems to be working OK. I've cleaned and oiled her. I think that she needs her motor looked at. Perhaps the carbon brushes need to be replaced??? How do I do that? Where can I find new brushes? Any other suggestions of what the problem might be? Please help...thanks.