Chapter 9 — MAINTENANCE 



of a given reading with readings obtained pre- 

 viously, and with the initial reference standard 

 test indications (part I), will reveal any signifi- 

 cant change. It is expected that from time to 

 time readings will show some changes. Minor 

 variations do not necessarily mean that the 

 equipment is not operating properly. If, however, 

 a particular step shows a reading that varies 



progressively in the same direction every time 

 the check is made, it is an indication that the 

 equipment is not in top condition, that a failure 

 may be about to occur, and that corrective 

 measures should be taken. At such times the 

 technician should refer to appropriate manu- 

 facturers' instruction books for service and 

 repair procedures. 



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