I had an accidental disengagement on my millie some time before, when I chopped a one inch diameter branch to cut it off. It was also a bit of a test and I chopped in rapid succession. I held the knife towards the butt of the handle and chopped with a loose wrist. I believe that the rapid successive impacts caused it to disengage. I was not able to replicate it though. BTW, I love millies. I have 6 of them.