My buddy just bought this bike. It has very low miles 5-6K, and runs mint except for this little problem. The hydraulic clutch seems to build pressure over the course of a day or two. It gets to the point where the clutch won't disengage. A simple release on the bleeder, and a pump of the lever, relieves the pressure and all is good again. He has flushed the fluid several times. It helps for a while, but he needs a fix. He downloaded the service manual, and is mechanically capable. What should he rplace first?