On my '03 R6, sometimes when attempting to shift down it feels like there is no gear there, I press the shifter but it just moves freely and doesn't click into gear, it just stays in the gear it's in. I sometimes get the gear back if I let the clutch out and pull it back in, although I have on a couple of occasions been stuck in 3rd at the lights.
I'm not sure where to start looking, any suggestions?