Try changing the clutch fluid, that cures the problem for a lot of people.
For the love of god do not change to an FN2.
Sorry to dig this up. I've got exactly the same problem in my CTR.
Just phoned local dealer - £1331 to sort out 5th & 6th, and replace 1st & 2nd synchro.
Think I'll look for a post 2004 gearbox....
Mine's an 04, May 2004.
About the gears crashing though, I've moved my seat one click forward and it's got rid of 95% of the occurrences. Still it does play on my mind...
email me if anyone wants help fixing their gearbox!
So a simple gearbox oil change solved the crunching?
That would be a relief if you were expecting a new clutch/box