I may be dumb but I'm not stupid. After the second clutch cable I figured out what was missing. 
I think that at some stage we have all done dumb things, I'll tell you one day about the really, really loud tappet rattle that resulted from installing the rocker shafts upside down on my R100. Fortunately new shafts/axles are not too expensive and I had lots of stuffed bearings to play with whislt making up a press to change them.
Or I could talk about what happens if you don't do up the gear box output flange to driveshaft bolts tight enough
Or how much pressure it takes to completely strip the thread from a final drive drain........
And those art just a few of my "clangers" ,