from doug
"Hi !
I am embarrassed to say Yes. I do remove the knob to extract the unit
from the case. It seems the set screw did not get tightened as much as
it should have and this caused it to fall off. I am truly sorry and I am
willing to help if I can, just let me know...thanks and once again, I am
sorry...Doug"
At least he admits its his fault. He'll get my business in the future!