exterior light covers

[Gizmo100]

I did my first run of the WD anti sway hitch. Everything went well just need to do some fine tuning. When I arrived home I noticed I was missing a upper light cover

I pulled off one of the lower cover to look for part numbers. The first thing I noticed was it came off fairly easy. It appeared to have 3 little  spots of sealant that may have help hold it on. I removed the sealant and the lens slips on and off with no problem. That to me is a problem. I'v look over the cover and base. I don't see any sign of damage

Any Ideas on a solution to keep the covers from falling off

 

[John From Detroit]

GOOP and only a spot or two