I know a similar story, told to me by a Scots friend from the Gorbals. He spent some time driving an engineer around who had lost his licence through the drink. He fixed turbines. The sort that ventilate factories. He said blokey would go into a factory, ask them to switch it on, watch it for a few seconds then say, "Take the covers off and get me a ladder" then they'd go to the pub till that was done. Once they got back to it, he'd ask for it to be switched on again, watch it again, get it switched off, climb up the ladder turn it round until he got to the problematic blade, size it up then give it a big whack with a lump hammer. Then off the ladder, switched on problem solved. Back in those days he'd charge a thou or so for that. The customers would say, "But, but, but all you did was hit it with a hammer!" to which he said "Ah, but it is knowing which blade to hit, where and how hard. would you rather pay two or three times that for a new blade?"
I may have got the money bits wrong this was over 40 years ago!
Luv this sort of stuff.