Francis Searchlights Voyager 2 User Instruction & Installation Manual page 12

Release the M4 knurled nut that secures the front lead to the
positive end of the lamp.
+ Positive end of the lamp (FRONT)
M4 knurled nut
Keep the knurled nut in a safe place as it will be needed later.
Now that the knurled nut is removed, the front lead can be
released front the thread on the front of the lamp.
The lamp can now be removed from the rear lampholder by
carefully unscrewing it. When fitting the new lamp, the negative
end must pass through the ring terminal before being screwed
back into the lampholder.
The new lamp must be handled carefully, and a suitable
protective cloth must be used when handling the lamp. The front
lamp lead can now be re-attached using the M4 knurled nut. Do
not overtighten the nut.