I've been having a problem recently with the rear gears on my Veloce set-up. I find that occasionally the thumb lever will refuse move and change gear. To get it moving again I need to press the lever shifter a bit to un-lock it, then it will carry on be fine. This only ever happens after I've changed into an easier gear eg approaching lights, but not always. Is is me pushing the lever shifter too far, and only pushing it half way through a gear change, or is it the lever itself getting stuck. It's only a few months old, but it's always felt a little more "clunky" than my previous Veloce levers. Do they need a bit of lubrication, or could it be the cables?