Well would you believe it! When I posted "Cracking up" yesterday I was only concerned that the spate of reports of broken knobs on Elecraft K3s meant that there was something wrong with them and that I and many others would eventually become victims. I didn't think there was anything wrong with the knobs on my K3 serial number 222 at the moment. This morning, just for the heck of it, I put my magnifying headset on to examine the knobs more closely. The first three were OK but when I examined the RF/SQL SUB outer knob I could see a hairline crack going through the set screw hole from front to back.
You would never have known it by turning the knob but the crack is clearly visible (especially if you click the image above to see the full-sized version) and can be closed by squeezing the knob (which has now made it a bit loose.) I think this is a more extensive issue than most people realize, or than Elecraft is claiming. If you own a K3, check the concentric knobs with a magnifier. You might be as surprised as I was!
Dave G4AON just sent me a picture of the AF knob on his K3 after he removed and tried to replace it.
You don't need a magnifier to see the problem with that one!