6. Remove the old O-ring (MP15). Clean the O-ring surfaces of the battery cover and the instrument case. Install the battery holder on the battery cover, then install the new O-ring. 7. Remove the four Pozidriv® screws (H7) and rubber washers from the bottom case. 8. Lift the bottom case off the instrument, and remove the O-ring (MP13) between the top and bottom cases. (Always install a new O-ring prior to reassembly.) 9. At this point, all calibration adjustments are accessible through the openings in the side of the pca shield. Refer to the calibration adjustment procedure later in this chapter to calibrate the instrument. 10. Remove the four Phillips-head screws (H3) at the bottom of the pca that connect the pca to the input terminals molded into the top case. 11. Carefully lift the upper end of the main pca and shield assembly to disconnect the assembly from the digital pca, then lift the main pca and shield assembly clear of the case.
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Figure 3-3. Switch Extension Shaft Installation
12. Note the position of the rotary switch extension shaft (MP17). With the rotary switch in the OFF position, the single small pointer on the base of the extension shaft is pointed toward the top of the instrument. Refer to Figure 3-3. 13. Lift the rotary switch extension shaft (MP17) off the rotary switch shaft (the shaft on MP2). 14. Remove the E-ring retainer (MP6) and the detent spring (MP5) from the rotary switch shaft. 15. Pull the rotary switch knob (MP2) out from the front of the top case (MP1). Take care not to loose the Teflon bearing washer (H1) under the knob. 16. To replace the O-ring (MP4) on the rotary switch shaft, cut off the existing O-ring without scratching the metal shaft. Clean the shaft thoroughly, and slide a new O-ring over the shaft into the groove on the shaft.
