Looks like the grey stuff on the gasket maybe some kind of gasket sealer?
I agree with the comments about the circlips, they look a bit crude and loose, maybe a failure point in future.
Searching on Google I found a type of circlip made my Carillo called Kranm Lox, see This Link
, the tool comes complete with a special installation tool.
Interesting video about these circlips Here
These circlips are listed on page 185 in the Carillo catalogue located Here
, so I assume you can order them from your local Carillo dealer or direct.