The plastic key that locks the barrels slides out of the metal spacer, these are not a tight fit so be carefull when you dismantle the barrels.
Reassembly, basically the reverse of dismantling, watch for the odometer reset mech, this works by the remote cable pushing a chamfered shaft up into the side of the spring mounted gearing to disengage the odometer from the trip meter and meshes a new gear to reset.
The face was sandblasted and given 2 coats of metal primer and white top coat ready for the new dial faces.
Next the center gauge set, i removed the air vent deflectors, the light blub holders then the retaining screws from the mount.
The outer housing comes free, then the middle 'tray' with the light tunnels for the ign, handbrake etc, then the back plate with the gauges.