I made one out of a piece of flashing. I folded it over a sturdy wire, loose enough to be able to slide the wire back out. Then I drilled a hole on either side of the plastic housing. I put the cover over the hole, slipped the wire through one side of the housing, through the metal cover, then out the other side. I then bent each end of the wire so it couldn't pull loose. Ta Dah - simple economical fix!
You can even use the existing turn buttons to hold it while traveling (if you remember)
2008 189FBR & 2014 FORD F150
Tons of Inexpensive Camper Mods WackyPup.com