They work with or without the preload. I like the preload in there so I know everything is held snugly in place under no-load conditions. It's not imperative, just good.
As long as your gears were not installed backwards, like mine, and others, had been, you will be fine. As far as the circlips go, my axles snapped in with no problems other than one side was tighter than the other. Yes, there is some play but it's not evident during use at all. I made sure the circlip grooves were towards the center of the core when I placed the side gears during surgery. Maybe I just got lucky.
I THINK, that in your ME: picture,
your circlip grove is towards the outside of the core...just taking note. Am I right or are you right, I don't know. This will be your contribution to this thread because I won't be taking mine out to check anytime soon.