Thanks Cedric.
Yes, the spring is between white and black parts of the lid. There are more pictures here: Golem Radial Scrubber for the Meg
We played with various waterproof materials, but WOB was not acceptable in any. My opinion is that if you have so much water in the scrubber, the loop is usually copromised and it is time for SCR or OC. The sensors will most likely be shot as well. The radial scrubber in Meg could potentially still function even when the can is half full of water (you just have to make sure to keep it there and not move it into your mouth ).