I have a MTS 620 that for the most part been quite reliable and easy to maintain. Recently it has developed an issue that I can't get a definitive answer to. When the 620 reaches operation temp. (190-220), the clutch hesitates for several seconds to disengages when attempting to down shift. It sometimes takes a tweak of the throttle to break the clutch loose. I have followed suggestions of bleeding the slave but after a complete pint of fluid the problem persists. Mind you it only occurs at operating temperature. Has anyone experienced this problem and found a reasonable cure.