It doesn't take much of anything to make an ice blade junk. A few years back Strikemaster was using Chinese blades instead of the Swedish blades they were using. Those were junk right off the pile. I have no clue what a rhombus angle is, and apparently the good people that make the machine don't think it's a big deal, or they would have calibrated the fixtures, and they've been making this machine for 30 years. I've been sharpening blades for 5 years now and I've never had one come back because it didn't cut well. I have to follow the angle that is there to begin with, and if that was screwed up from the start, you're just multiplying the screw up. I can't see what's going on with that blade because I don't have it in front of me. It may have been altered, maybe they were ground by hand, or it just may be that too much has been ground. You can't see what's going on down that hole. You need to complain to the guy that sharpened them for you, because you're not going to sharpen them by yourself. Now I'm heading out to walk on the water, hope they're biting.