My friends gifted me with a new Singer about 15 yrs. ago. Of course the book said to use only Singer needles. Up to that point I never had a problem mixing my needles. This time, however, the length of the needles were so different that I manage to screw up the bobbin casing and had to completely replace it. I worked for Singer on all of their machines in the 80's and have worked on numerous machines, all different brands, since. That was the first time I ever ran into that situation. Now I have a little Bernina and am in love.