In 1981 I started mending the "BBC Micro" as a buisiness having got experience and contacts by previously working for Acorn Computers.
Local shops and private customers and Acorn used to send me machines to fix. By that time I had fixed a *lot* of machines, so many that a) No one believed it. b) I had seen "every" fault several times e.g. there was a worse-case design fault that only I knew off (I collected five machines over a year with the same fault and eventually "found" the problem by changing every IC: there are over a hundred in a fully populated board + two ULAs - they all had a Texas chip in a certain place which, when replaced by a National part "fixed" it, the Texas part was faster so I emulated the Nat' effect by slewing ph1 with 100p cap ).
One of the ULAs, the "video" ULA was originally notorious for a certain problem that occurred when it got hot but most were replaced by 1982.
In 1983, a chap who worked for a local shop brought in the usual weekly delivery of about a dozen machines and pushed one toward me saying "It's the video ULA".
Now I *knew* that it wasn't and also non-thinking sheep-like psuedo tech-talk like this annoys me so I said "Oh no it isn't" and proceeded by "fixing" the above worse-case design fault (adding 100p to phi one) and then heated the board with a heat gun - it had no effect so I took the mod off and then ran my three proven memory tests again with the board hot - they had no effect so I had no option but to try a new video ULA and it worked.
So for the next two years Billy, for that is his name, never let me forget it. "Need any help fixing computers Robin? Heh heh." "Had any duff ULA's today! Heh heh." etc.
All this grief could have been avoided by my saying to Billy, at the outset "Hey, the video ULA? I never thought of that. Let's give it a try." But Billy knew me for the vain idiot that I am and so probably set this as a trap from the beginning :(
So the moral of this story is: If a customer says "xyz jumped off the table and squirted cider in my ear." Then I for one will believe them, if only for my *own* protection.
Cheers Robin