I have seen those little slots so gummed up it isn't funny - took a lot of going over and over with solvent to get all the gunk out. Once you get it to move freely put some T-F on it where Joe shows it. If you use SM oil or 3-in-one oil expect to have to do this all over again. SM oil has paraffin in it. You might be able to just heat it and get it to free back up. These Singer 401, 500 and 600 machines have to be regularly oiled and regularly cleaned to function optimally IMHO. Maybe that is why I love my Singer 403 and the 503 so much - they are more forgiving and I am so lazy.