Panerai with power reserve: Cal.7750 base
Symptoms: Immobility (spring broken)
Repair contents: Overhaul, spring and gasket replacement, case cleaning, waterproof inspection
Repair cost: 33,000 yen
I disassembled it. Panerai has their own movements, but they used to sell models based on the ETA7750. In the case of in-house movements, if there are parts to be replaced, the manufacturer will repair it, but if it is based on ETA, some parts can be obtained. Some parts that have been changed to original ones cannot be obtained, so whether or not it can be repaired depends on the nature of the malfunction.
This is the back side. The gear at around 5-6 o'clock is the power reserve. It is engaged with the mainspring to display the duration. I think this part is original to Panerai.
Assemble. The base movement, ETA7750, has a chronograph, but that mechanism has been removed to make it a simple automatic winding. The mainspring had broken, so it was replaced.
Assemble the automatic winding rotor, then attach the dial and hands. The power reserve will tell you how much power is left in the mainspring, so it should be easy to use.
I hope this will be helpful for your repairs.