Last time I noticed that water is leaking in my case. Lens was all foggy. I’m not having original gopro case, but I had same problems with original case. Gopro 3 cases are not so durable as old cases. My original case cracked so I bought chinese case from ebay. Case is OK, maybe just not as good as original, but worth of money I paid.
I decided to seal a lens with car gasket sealant. It is very durable so it should do the job.
First remove lens:
Apply sealant:
Install seals:
Add more sealant on the top:
Install frame:
Put some sealant on lens:
Screw back lens ring, do it gently, you don’t want to break the lens:
Then just clean it with paper towel and leave it for at least 8 hours. Drop case in the water without your cam to check for any leaks.