I was able to remove the 3/4" lens by gently working the tip of an exacto knife around the seam. You'll discover where the seal failed as the water inside will start weeping out. Focus the tip there, trying to get the knife tip under the glue gap on the edge and then work around the circumference until enough of it is free to pull it loose of the failed adhesive. The key step is finding that one place where the water will leak out, and working your exacto blade tip in. Try twisting the blade as you gently lever the lens free.
I'm using a bit of silicone seal to reinstall it after I'm sure it's totally dry.
Update: I sealed in the lens, powered it up and the lens promptly fogged up. Had to dig the lens back out before the sealant dried. Have powered the device up lens free in a protected location and will leave it there several days before revealing. It's producing a perfect image but led is red.
Update 2: Even after leaving the thing in a bag of rice for a week, and letting it sit in the hot sun, I still got some light fogging after resealing and powerup. Fortunately it was very light, just around the outer periphery and after a day of operation finally cleared up. While that's good news, probably means the unit is not 100% water tight, and might refill again, next rain. Rain is forecast for this Weds, so I'll update accordingly.
