TM 5-4220-231-14&P WARNING All   repair and maintenance should be    followed by    a   thorough inspection and testing of   the equipment to   ensure its  full   operability and    safety. WARNING Ensure gages are depressurized prior    to   performing replacement procedures. WARNING Exercise extreme care when handling pressure gages. Failure to   keep gages, tools, and parts free from oil,   grease, rust, or   contaminants may cause damage or    inaccurate readings. Failure to observe this    warning may result in   equipment failure, or   injury    or   death of   personnel. WARNING If in  doubt about serviceability of  a   part,    repair or   replace immediately. Failure of   a   component part during a   dive may result in   diver injury    or   death. Use    only approved replacement parts. NOTE Perform component replacement procedures in   clean environment. NOTE Approved reentry control procedures must be used for   component replacement procedures. 3-21