Author here. This gave me a chuckle. :)

And, yes, that's pretty much it, although "rebimboca da parafuseta" is less obscure than "reticulation of the splines" (if you're Brazilian, anyway).

It is used to denote a fictitious part, which name or function are unknown, of a car engine or any other machine. It was coined in the 70s TV show, and later used in some ads aired during the same period; since then, it's an expression used for humorous effect. It's not very common these days but is unlikely you'll meet someone down here that never heard it.