What type of hood do you have? If the classic stud type not easy up then check how secure the hoops are. Mine are held down when the hood is not needed by leather straps and rattled until I discovered the straps not fastened.
It's an M3W
2009 4/4 Sport Henrietta 1999 Indigo Blue +8 2009 4/4 Sport Green prev 1993 Con Green +8 prev