Gently and progressively lift the back plate off the pillars joining it to the front plate. As you do so the pivots of the gear train will be released from the pivot holes in the rear panel.

As you lift off the rear plate some of the gears of the gear train may lift out of their pivot holes in the front panel. If so, gently remove them and reinsert them temporarily in their pivot holes in the front plate.

You will now have a forest of arbors. Take a photo of the gear train with the rear plate removed, or maybe several from different angles. This will be greatly helpful on reassembly.