TBH I don't really want to ask the question because I am worried about the answer having had the gearbox pulled out just over a year ago for a broken shift fork.
Anyway, I have noticed (today) that pretty much on each and every gear change up from 2nd into 3rd gear that the gears crunch. It doesn't do this on any of the other up-shifts and it doesn't do it on any of the down-shifts not even from 4th to 3rd either.
If I up-shift from 2nd to 3rd abnormally slowly then there is no crunch, but on a normal shift it crunches.
I have two potential causes in my head: syncro-mesh or dogbone bush?