When I purchased my Disco, it had a cheap compass on the dash and the mirror compass worked as well. As of today, suddenly, without notice or warning, the mirror compass ceased working; there is no compass fluid anywhere to be found (if there is any), and I have to say, I miss the darn thing. Has anyone had experience with the diagnosis and repair of these things? Cheers and Rover On!

 

Checked fuses?

 

From a Landyzone.co.uk page:
Vanity and rear view mirror

With the ignition switch in position I or II, the feed from fusible link 7 passes through the
auxiliary circuits relay contacts and is connected on a WG wire to the passenger
compartment fusebox where it passes through fuse 15. From fuse 15 the feed is connected
on an LGW wire, via header C0286 LHD/C0291 RHD to the interior mirror.
The power supply from fuse 15 in the passenger compartment fusebox supplies power to
the interior rear view mirror. The automatic dip function of the mirror can be selected on or
off on the mirror. The mirror is connected on a B wire to earth header C0706.
When reverse is selected, the feed from fuse 25 in the passenger compartment fusebox
passes through the reverse switch contacts and is connected, via header C0287 LHD/
C0294 RHD to the interior mirror on a GN wire. This supplies power to the interior mirror and
changes it from its dipped to normal condition when applicable.
The interior lamps operate independent of the ignition switch position and can be operated
manually or automatically when a door is opened.

 

Fuses are ok; however the most forward fuse, showing the (second) engine symbol ( number R6) is missing. Unconnected to the mirror, I ask, should it be?

 

Which fuses did you check? There are the ones in the engine bay and the ones under the driver's side kick panel.