I had read reviews on the Vector that mentioned the head coming loose while shaving. I've made sure to check after every rinse between passes and haven't had a problem.
Until today.
After many excellent shaves, it happened to me. The head spun while maneuvering under my nose and gave me a nasty cut on my upper lip. Still weeping more than 6 hours later.
Has anyone experienced this? That may be the risk of not having full threads. Sadly, for me, it is now retired. A cut from doing something careless is on me; a head coming loose isn't.