EXFO FG-750 - Manual (Page 45)

Getting Started with Your Fiber Guardian
Fiber Guardian 31
Inserting or Removing Optical Switch Cassettes (Certain Models Only)
6. If you have not done so already, clean the optical fiber connector
located at the back of the cassette. For more information, see Cleaning
and Connecting Optical Fibers on page 77.
7. Insert the cassette through the top opening.
8. Connect the cassette to the unit using the optical connector at the back
of the cassette and the corresponding optical fiber.