Angilion, what do you do for a living? You seem to have a good knowledge of the subject!!
I maintain and repair fruit machines for a club. Also change machines, pool tables, anything of that kind. I'm at the bottom end - single site work - but trained to a higher level because (a) I prefer to be and (b) my immediate superior in the club is a bona fide fruit machine engineer with 40 years experience, so I've learned a lot from him.
Easy job, badly paid. In essence, it's cheaper for the business to have someone on hand for most jobs than to have machines out of play for up to a few hours until a mobile engineer can get to them. Most faults are mechanical and can be fixed by disassembling, clearing and rebuilding the relevant part. Much of the job is actually customer service rather than the machines per se, because of the nature of the business (it's a bingo club).
The newer machines are usually boring to work on - anything other than a jam is either a software fault or a simple case of locating which component is faulty and phoning for a part. We aren't allowed to keep spares other than light bulbs and tubes because they cost money, so I can't even replace the part myself.
The older machines are more fun, because parts are hard to come by and you have to improvise.
They're all badly designed in one way or another, though. I'd love to be able to phone whatever incompetent buffoon designed each machine and phone them to come and fix the easy problem made into a lengthy and fiddly process by their design. An example - Astra Section 21 cabinet (Section 21 doesn't exist any more, but the machines are in use after being converted to one of the new types). The buttons are quite easy to take apart and they use a standard microswitch, so replacing a broken switch in one is quite easy...except for the start button, which is the one that breaks most often (because it is used the most). Access to that is blocked by a steel plate welded in place, which the note acceptor is mounted on. So the only way to access the start button is to disassemble the front of the cabinet, remove the lower front section and access the button that way. Putting it back on is a fun job on your own, as you have to hold a fairly heavy steel and glass section precisely in place while screwing it back in. Or the wonderful cabinet designers who bodge up a method of using two plates and six bolts to attach a note acceptor at the front...which is where it opens, so you have to take the whole thing out to clear a jammed note. Oh, and it appears that there are strict rules about the length of cables. Any cable must be either half an inch longer than is absolutely necessary, so that it has to be connected or disconnected solely by feel, or eight feet longer than necessary, so you have no idea where to stuff the reams of excess cable to make sure it doesn't catch on anything.
