Prepering your equiptment for a dive
For this example we will talk about a housing with only 1 user servicable o-ring although this can be applied to any user servicable o-ring.
Firstly open the back door of your housing and remove the o-ring.
Before we start doing anything to the o-ring we need to make sure that all of the serfaces that the o-ring will be touching are clean. To do this you can wipe them with a lint free cloth or paper towel. The serfaces want to be as clean as possible.
Now we want to clean and grease the o-ring.
The grease helps to loosen dirt, acts as a preservative, and allows the serfaces touching the o-ring to slide into place easily. Surplus grease simply acts to collect dirt.
Put a small amount of grease on the o-ring, start with a blob about the size of a pea, for larger o-rings you may need more grease. Spread it around and cover the entire o-ring, there should be no dry spots.
Now wipe it off with a lint-free cloth or paper towel, the o-ring should be left with a thin coating of grease. This is generaly sufficient .
Now replace the o-ring into the groove. Before closing the door you will need to make sure that there are no hairs or small bits of lint on the o-ring, once you are sure it is all clean you can close everything up and you are ready to dive.
There are a few systems out there that glue the o-ring onto the groove but these systems are fairly rare.
For these systems you can wipe grease around the o-ring and clean the groove. You will still need to make sure that there is no hair or lint stopping it from sealing properly.