A transmission has a housing with interior and an exterior surfaces. A fluid passage is located in the interior of the housing. A ball-check assembly has a ball; a conical retaining chamber with an end with an inner diameter greater than the diameter of the ball, and an end with an inner diameter less than the diameter of the ball; and a conical wall extending between the two ends. The fluid passage is in fluid communication with the ball check assembly. The ball is located in the conical retaining chamber and is dimensioned to become wedged against the conical wall as the ball is moved from the greater diameter end toward the lesser diameter end, thereby providing a seal between the ends of the conical retaining chamber.