I buy them all the time. I changed the blade just today, and had problems with it not cutting. It wasn't the blade
but how it lined up in my cutter. I loosened the screw, wiggled the blade (carefully, as to not cut myself)
Tightened everything back together, and away I went. It just wasn't lined up right, and wasn't rolling when I cut
with it. I could tell, it was 'pushing' the fabric. Hope this helps anyone that has had a similar problem.