The mention of gaming machines & the use of random, in the early 80's I did a lot of work in that industry, although not specifically on fruit machines or other AWP (Award with prizes), mainly on repair & upgrading the likes of Space invaders & all the newer types of machines, I did learn that during the boom of using stepper drives controlled by microprocessors rather than pure electro-mechanical systems there was as such no randomness as far as pay out.
These machines could be set to pay out a percentage of coinage put in.
In other words, a machine could be programmed to pay out 74% (think this was the allowable range for a licence) of the coinage throughput, the pay out percentage was mainly controlled by the features system i.e. perhaps if the money in versus the money out was 75% or above it would enable the features, this resulted in a larger than normal pay out via the feature.
I do remember some trials (I was not involved), where a group of people played these machines, it was obvious that most people win a little put it back so for example for every amount of coinage in only 75% is paid out, in reality the actual pay out is probably 0.001% as people put back any winnings in the hope of a big game. In essence if £10.00 is played it is possible £7.50 is paid out, this is then put back in & so the average pay out will be 75% of that £7.50 & so on.
Yes there may have been some sort of pseudo random algorithm but it was strictly controlled, I worked with a guy who was in a team who developed a new style of gaming called award with skill, this in essence would get round the gaming laws & controls for example no licence needed or the current controls, there was a very long & expensive court case in a part of the UK regarding this, the outcome appeared to favour the developers, in other words it was not gambling but awards were based on skill so could not be classed as gambling. One feature of this was to effectively control the pay out so that the machine never actually lost was the prize started off low for example if 50 pence was the stake then the pay out would start at £1.00, as the money throughput increased, though no winners this increased surpassing the pay out limits of the current gambling legislation, however, once won the jackpot would revert back to the lower level. as this was not gambling then the jackpot could be very high.
I did meet a guy who was an expert on the second world war, there was a game based on questions for that era, his nights out consisted of going round the bars, waiting for a reasonable jackpot & win most of the time, it was reckoned that he made a good living out of it.