A bit of further investigation into this one......
Look, think about it - there were nearly 8,000 £1 coins piled up in the cash box. This meant they were touching the electrical contacts at the bottom of the middle section, thus shorting the thing.
Right, these £100 prize machines were pretty much lifted from the coding scripts of club machines and didn't use the same code as say the older £15 or £25 JP ones which would allow 50 or 75 streaks. A club machine would not allow a jackpot repeat. So in that case the illusion of a £100 repeater would be a kind of 'false advertising' on the glass and you would only get the single £100 from a 'white' value (as you did before).
I have an idea here - I once encountered a chap from downstairs from the flat I used to have about 25 years ago, looking very upset. When I spoke to him a few days later, turned out he's been in an arcade in town playing a 10p conversion of an old £5 jackpot slot and had spent several hours and £200, all he had that week, trying for the £5 jackpot repeater. He basically described (he didn't have the 'knowledge') all the symptoms of a coding block, he had apparently repeatedly got to 4 quid on both the number ladder and feature board and lost going for the £ JP repeater every time on 2 or 11. I explained that due to lower turnover on these reduced stakes of 10p, the arcade's percentages were set as low as possible and that this alone would block the feature rather then any specific coding.
This is something I proved beyond doubt a couple of years before. I bought a club £150 JP machine as it was identical to the one that used to be in my local snooker club and always dropped in the cashpot between £80.10 and £81.00 (it would never get to £150 on the percentage setting they had it on.) As with the Scorpion 5 board, you had a a default legal RTP minimum setting of 70% and each of the 8 dip switches added 2% for a max of 88%. On the top percentages you could never, ever gamble to the top 3 features as they were blocked, same as the £100 RED was in your case. You could however on some of the lower percentages (I recall the owner used to take £50 off of players who attained the 'reel skill' feature which was second and he could stop and hit all 4 triple bars for the £150 which was no mean feat...) and on the higher percentages it 'switched off' the £80-ish cashpot guarantee.
I reckon this is where your Andy Capp issue could lie - as you demonstrated you can get the equivalent feature up the top which simply would never repeat, so why not the bottom one do the same? I think your feature attempt was simply blocked via the 86% setting - if you can simulate play as you did with your bot, the same method, but successively trying the different percentages in order, I reckon you may might well see it land on it - even though we know it will never repeat.
) and can't help myself when this sort of stuff gets posted!
