Not a fruit machine as such, but I could win the Spot the Difference game every single time on the old IT boxes. I travelled everywhere I could to try and find them to empty them.
It was partially down to simply crossing my eyes to put each picture over the other. However in the original programming on the levels where you have like 3 seconds, I found out that it would not trigger being out of time if the animation was still circling the previous difference when you pressed the next one.
I did this so much that they banned my name from the leaderboards. It’s still the case even now. If you ever play it on the future, try putting my username to the right here in and see what happens.