I have just replaced the O rings (with replacements from OpenROV). The fit does not seem to be nearly as right as before. I did use underwater camera O ring lubricant on them which I had not done before.
If the retainer O ring for the main tube falls on the joint between the endcap and tube it is enought to move the endcap outwards.
Any suggestions ? I am diving shallow - 20 feet or so and getting a small amount of saltwater.