Noticed while driving home last night that the gear changing both up and down gear appears to be more clunky and noisy than it has been in the past. Noticed also slightly more difficult to get the bike into fourth and fifth gears when changing up and then getting into third and second when changing down. Cluth appears to be engaging and disengaging at the same point when I pull in or let out clutch as previous. I'm changing up gears at recommended times according to bike manual - 20kph for 2nd, 30kph for 3rd, 40kph for 4th and 50kph for 5th. Also changing down gears at recommended times according to bike manual - to 4th at 45kph and 3rd at 25kph. Stood bike on centre stand and let it cool down, checked the oil level to determine if this was low and therefore affecting gearox, oil level ok. Anyone any sugggestions where to look?