Having sold tens of thousands of replacement lid knobs at this point, we’ve only have a few reports of the embedded nut not having any threads. Obviously, that defect is a show stopper and you should contact us for a replacement.
However, you might discover difficulty screwing the knob all the way down like customer Frank did. At first we thought it might be defective nut threads. But then Frank figured it out.
After I wrote this morning, I had the inspiration to shoot some WD-40 on the threads of the lid and into the threads of the knob. I unscrewed the knob, put the lubricant on, and tried again — and it went further. I did that several more times and each time it got closer to the bottom of the threaded post… and finally got the new knob to go all the way down to the surface of the lid. Hooray!
Turns out that when the old lid knob nut inserts rust to the screw, some of the rust can remain behind and impede the new knob from screwing on all the way.