I work on a rental fleet, and we found that most adhesives wear out after a while and you have to re glue them. We tried contact cement and it works extremely well. You'd tear the foam long before it would fail. Kinda tricky to work with, though. Have to keep off the lens of you're effed. If you're replacing the lens though, just use the cement before replacing and if you ruin the lens, who cares, you're changing it anyway.