I have had my Nils since they came out. Through the years I learned you need to send the blades out to this certified sharpen guy in Mass or buy new head. I usually buy a new head for around 90.00 dollars, which might be a little more but i do not have to worry about the angle being off. I have had my sharpen a couple of times by so called professionals and they completely took the angle off the blade and ruined the head. So be careful who you choose.