Methods of positioning an optical unit in an optical package are provided. The position of the lower end of the regulating member is higher than the cassette attached to the main body, and lower than the lower end of the feeding roller, and the position of the upper end of the projection preventing member is higher than the position of the lower end of the regulating member. The apparatus further comprises a second spreader, and wherein the proximal end of the I-beams is connected to the second spreader. The spring assembly has a first member that engages the internal mode switch to prevent the internal mode switch from rotating and has a second member that engages the internal mode switch to prevent the internal mode switch from rotating if the first member does not engage the internal mode switch.