It is mandatory to check the o’rings to keep them clean and lubricated. The double o-ring guarantees the camera waterproofness and must be always checked.
Wipe off the o-rings gently, being very careful not to stretch it. Use your finger wet with clean water or saliva. Do not attempt to use salt water. Wash the o-ring off if it has sand on it that won’t come off, or if it is really dirty.
Relubricate the o-rings and place the them back in, again being careful not to stretch them.
Do not over-lubricate the o-rings. Just a little bit is fine. Make sure you use appropriate o-ring grease.