A couple of times now when I have been fitting or removing the lens hood on this unit, I have had the retaining screw come undone, (fortunately been inside at a table).
I have found that the screw needs to be fully backed out when trying to remove the hood but if you back it out to far the very small locking screw on the inside can come undone and if you were in the field when this happens your chance of recovering them will be nigh impossible. Has anyone else had this problem and have you seen any comments elsewhere regarding this.