Pinball machines, for the most part, do not require any lubrication. Most parts run "dry". Far more damage can be done to a pinball machine by over-lubricating, than by under-lubricating. As a rule, if in doubt as to lubrication, don't do it! Throw that WD-40 away, it won't be used here.
The only parts that will require any lubrication are metal-to-metal moving parts. There aren't very many in a game. Only ball eject and slingshot hinges. Use 3-in-1 oil on these if you must. But try and keep that lubrication in the tool box and away from the game.
If some prior person did lubricate the game, the lubrication has probably now congealed with the infamous "black pinball dust" to form a thick, black mess. This is unrepairable on coil sleeves, and new parts will need to be installed.
Ole
P4P