From what I can see on your partial file you uploaded, your cutting surfaces look ok.

Maybe there is some problem with the knurl part instead - I can't really tell that from a screenshot though.

A couple of things you might try are to use Construct > Curve > Isect to generate intersection curves between the knurl part and the cutting surfaces and see if there are bad looking intersection curves in some areas, then examine more closely in those areas.

Also you could try removing chunks of the knurl and trying to trim a smaller piece of them at a time to see if that is successful and might help to narrow down a problem area.

Another thing to try is to select everything and scale things up by 10 times in size, it could be possible that the knurls are small enough that they are running into some tolerance problems.

At any rate, those are some of the things that I would be doing to the file if I was examining it myself.

- Michael