Never loose one again!
When u get another one I strongly recommend removing all deflectors, give them good clean then make sure they're completely dry. Buy a good clear silicone sealant (one for upvc windows preferably)
Run a small (don't need much) bead along the whole front edge that fits up into the rubber,
Carefully insert deflector in place (push it away from rubber when inserting to avoid mess) once pushed up fully in place pull towards u to make contact, when happy it's all good do the window completely up still pulling deflector towards u. The window will obviously lock it in place and squash silicone completely flat creating a perfect seal and a good strong bond! Use a wet wipe to clean any excess silicone that may have come out (I didn't get much come out as u really don't need a great deal) the water in wet wipe helps smooth any excess neatly between rubber and deflector.
Leave all windows up for at least 24hours.
This will leave a sound strong bond once dry. (Having someone to
help makes it 10 times easier)
U can practically hang off mine (well not really but u get what I mean lol) they really don't move at all and I'm completely confident they'll never come off until I yank them off which I won't
Took all of about 30 mins to complete job. Hope this helps........
Hint: don't put silicone to near the top edge as u wouldn't want it getting between window and deflector!
Just a thin bead in the center worked fine for me.