As I understand it, a fruit machine (class C) is not the same as a slot machine, there’s no random number generator in a chip which determines the payback percentage and every spin is an independent event.
So, a fruit machine should be ‘due to pay’ at some point. But, does the vary by the amount of your bet? A 20p bet is just the same as a £1 bet? Also, if there’s multiple games on a machine, is a potential payout based on the game I select or is each game considered its own and has their own calculation of when it’s ‘due to pay?’