A spinning rotor gauge is one of the most reliable vacuum gauge. The gauge is a noble viscosity gauge which is essential to a transfer gauge and a reference gauge in high vacuum. The gauge consists of a control unit, a sensing coil unit and a rotor ball installed in a tube. The rotor is operated frequently in a different pairing of the control unit and the sensing coil unit for convenience of transportation and use. In order to clarify the interchangeability of the electronic unit and the sensing coil unit with the rotor ball, accommodation coefficient of the rotor ball in the different pairing was measured preciously by a direct comparison with a reference spinning rotor gauge. Pressure measurements by the two gauges was simultaneously done by using a personal computer. While repeatability within 0.1% was obtained in the measurement of the relative accommodation coefficient, the rotor showed a slightly high value, 0.5%, in the coefficient in special pairings. Consideration of the experimental results in detail showed that one of seven coil units gave slightly high value in the coefficient. The coefficient did not depend on the control unit. Big tilt of the sensing coil units, about 15@degree@ from the normal vertical axis, also gave a slightly high value in the coefficient. Remagnetization changed the value of the coefficient occasionally. It seems that the coefficient depends on the mode of the rotation of the ball. A fixed pairing of the rotor with the sensing unit is preferable for a reliable pressure measurement by the gauge.