EXFO FTB-1 - Manual (Page 201)

Maintenance
FTB-1 191
Replacing Batteries
3. Install the battery as follows:
3a. Insert the new battery, respecting the polarity. You can use the
image appearing inside the compartment as a guide.
Note: When the battery is correctly positioned, its poles should be facing upwards
and be placed on the same side as shown on the illustration in the battery
compartment.
3b. Apply slight pressure to the battery to secure it in place.
4. Position the battery compartment so that you can see the two screws.
5. Place the battery compartment on the platform, making sure that the
bumpers and the shorter sides of the compartment are flush with those
of the platform. If necessary, slightly move the battery compartment
until alignment is correct.
6. Lift the mobile part of the compartment screws and, while applying
slight pressure, turn the screws clockwise until they are tightened.
Note: You cannot replace the clock battery yourself.
Battery poles