nor should we presume someone doesn't know what bebs sound like on there way out. ive had three Vauxhall 16 valve red tops let go on me before. ive also seen my father, who is a retired old school mechanic, nurse many a knocking motor into the garage for a strip down.
there is a lad around here who insisted on driving his 80 with bearing knock, he drove it to destruction, lasted about a month.
I also changed mine on my 80 when I heard the faint start of a knock when driving close to a wall etc. I used taiho bearings, I have well over 100000 miles on them now, I think the companys turnover was in excess of 40 billion dollars last year..
didn't a Chinese company buy out ACL?
when I changed the bearings the slight knock went away but the ticking was still there. a bearing noise will also go up and down with engine revs, the ticking doesn't, it sort of gets drowned out by the sound of the engine.
you will never settle now and be aware of every little engine noise, so I would change them. especially when its a couple of hours work and the whole lot can be done for about £85.
frank there is a train of thought that the top end ticking can be caused by a drop of oil pressure that the worn bearings have caused.