Had to drive on 1 4 hour round trip this morning with my dad to help him pick a load of gear up - due to his increasing incontinence, we had many a service station stop with machine playing opportunity

Anyway, I stuck to the 10p / £5 ers at first, for time and because I only had a few quid in change on me and didnt want to be changing notes and going for machines big time with my dad watching over proceedings. After a couple of wins on these, and breaking even on homers meltdown, I was about 6 quid up so with about 8 quid in my pocket I decided to try the 30p / £25jp machines at the next station.
Two quid into Space Invaders wielded a quick £6 out - decided not to carry on because I got more or less straight on the board and thought it better to take the quick profit, didn't like the look of the way the feature was playing.
Anyway, I then went on aanother machine whose name escapes me but it was in a blue new style barcrest cab, with a trail to 8, a super trail over 8, and 2 hi-lo sections on the number bands.
I put a quid in this and was offered a fiver so took it - but when I pressed collect no money appeared. Fumbled around int he cash tray - still no sign. So I felt under the hole the coins drop out of and felt what felt like a small tennis ball wedged in preventing any coins coming out. I fumbled around, and sure enough, I could feel plenty of coins wedged behind this ball.
So I prised and picked away, pulling out coins one by one - the ball wasnt for budging but I managed to pull out quite a few coins until I had a nice £17 in the payout tray - not bad considering I should have only won £5!
But this is a pretty sneaky way of getting money out of a machine and I can't belive it hasn't been detected - I assume someone has come and wedged it in, and once every day or so will come and prise all the money out, because if most punters win a quid or two and it doesnt come out they will assume the machine is faulty and walk off.
Has anyone come across anything like this before??