Most fiber optic problems can be attributed to the fiber optic contact becoming dirty; therefore most fiber optic connectors are designed to make the cleaning of the fiber optic contacts as easy as possible.
Usually with fiber optic assemblies you first “inspect the end face and if it isn’t dirty leave it alone”. However if the fiber is observed to have any dust, smudges, or oils, it needs to be cleaned.
The Inspection and cleaning process is normally simple and quick, with minimal tooling required, as is shown in this Engineering Guideline. If inspection equipment is not available, the cleaning procedures need to be implemented.
Manufacturers of the 304M connector will recommend and / or provide their preferred inspection and cleaning equipment, together with cleaning and inspection instructions. However this document provides examples of the some of the solutions currently available. Users are advised to contact the connector manufacturer for more specific cleaning instructions.