The clear reverse lens popped out of my passenger tail lamp. Someone else found the lens laying on the ground and is going to bring it back to me. The frame doesn't seem to have any adhesive residue . What's the best way to re-attach the lens to the frame?

 

honestly buy a replacment tail lamp

most methods of reattaching the lense will likely require some sanding and refinishing of the tail lamp surface to do it properly...... a lot of work when you can just buy a replacement.

 

Luckily the clear lens wasn't damaged. I thoroughly cleaned the mating surfaces of the lower inner portion of the clear lens, lightly applied super glue to the frame side, rotated the top of the lens into the frame and held the bottom down for maybe 30-60s. It seems secure but I'll let it cure longer. I already have 3 spare taillamps but their condition is slightly worse, just in case this repair fails.

 

Yea....seen that done many times. Any good super glue that actually "slightly" melts or mates the plastic together as it reacts will hold forever.