You probably dont want to attempt to get the plates apart so heres a cheat.
How to fix a broken wall clock.
Replace the batteries if they are bad or corroded.
How to repair an old wall clock if your wall clock is off you will definitely replace the new battery if it remains dead.
Small hour hand first then the minute hand.
Finally put those hands on which i totally spray painted black.
While holding the black box in place on the back of the clock put the new washer on the front then thread on the new nut on top of the washer securing tightly with a pliers or socket.
The first and easiest problem to fix is restoring the clock s battery power which is done by removing the battery from the back of the clock and replacing it with a fresh one.
Check the batteries in the back of the clock for power.
Put on gloves and pull the batteries out with tweezers or tongs.
Step 2 replace the batteries if the clock is running slow or it rings erratically.
How to fix battery operated clocks.
It is possible to install the battery upside down where the battery is.
Unless you oven dry the clock after this the springs will rust and your clock is in very bad shape with an expensive repair bill.
Inspect the battery compartment for corrosion.