I have a customer who said it now takes at least three turns around the can for the opener to finally get the lid off. She wants to know if there is a way to sharpen the opener.
Have you gotten the opener back from her and tried it yourself? I just can't imagine that it needs sharpening. I haven't had anyone state this kind of problem.
Sometimes I have to go around a can a couple times. Some people have said that it's due to how much glue the can manufacturer has used. Either that, or it's a dud. I know some people say they never have trouble w/ theirs, so if she struggles w/ every can I'd look into getting it replaced if it's under guarantee.
I have had lots of people tell me this after heavy use for 2-3 years. I think the edge must get dull or something. I think there was a bad bunch arround 4 years ago. Alot of my customers tell me that's arround the time they got their dud. My SIL's does this and I have used it. Definetly does not work as well as mine.
I agree- the duds are still out there BUT the glue the different companies use play a huge part on opening the cans. I've noticed the thicker the glue the more times you have to go around. My customers care about the lack of edges vs the number of times.