If you know what model your toilet is, you can probably download a manual or an illustrated parts breakdown from the manufacturer that pretty much shows all of the parts and how they fit together.
I have made it a point to download (or scan in) every document for my RV as a .PDF and placed them on my smartphone.
That way, I have all the manuals with me in the event of an issue while on the road. And if I find my way to a RV dealer while on the road in search of a part, I'll at least (hopefully) know what the part number is I need.
True; the documents are a bit small this way, they are at least readable when you zoom in.
I am also slowly starting to assemble a spare parts kit for emergency repairs. This became all apparent last week when I blew out a 3" sewer valve when dumping the holding tank (it's a complicated story).
Along with the traditional fuses and such, I am assembling spares like a toilet gasket kit, spare ignitor for the hot water tank, furnace, and fridge, spare luggage catch (those plastic things that hold the cargo doors open that break all the time), spare catch for the screen door, and so on.
The only thing that works on a RV is the owner...