If in the next few days you receive a knob and a jam nut that doesn't fit DO NOT FORCE IT.
We were forced to change nut providers (yeah, giggle giggle) due to a shortage at Grainger and the place I ordered from seems to have shipped the wrong thread pitch.
I repeat, DO NOT FORCE IT. I am aware of the situation. New ones are en route. I can drop one in the mail as soon as the new ones arrive. Just send me a message and I will take care of the situation.