You can see the build up of dust on the paper gasket under the light tunnels.
The perspex lenses are fitted with 4 small rubber strips to absorb shock and stop the lenses rattling.
The rear cover of the gauge cluster has a down lighter fitted in the top of the housing which illuminates the heater matrix controls sited below.
The light cover is held in place by 1 screw and a lug, the connectors have 2 screws and a steel underplate which locates in the lugs (see picture below).
The blue coloured light cover in the top of the housing.
The PCB style wiring for the light cluster is held in place by the light bulb holders and backing screws for the gauges, some of the mounting screws have washers to spread the load of the fixing over the plastic wiring sheet.
These are very fragile, so be carefull if you remove this.