𝗖𝗹𝗶𝗺𝗺𝗮 𝗖𝗮𝗹𝗽𝗲𝗱𝗮 𝗣𝘂𝗺𝗽 𝗹𝗲𝗮𝗸𝗶𝗻𝗴 𝗺𝗲𝗰𝗵𝗮𝗻𝗶𝗰𝗮𝗹 𝘀𝗲𝗮𝗹 𝗰𝗮𝘂𝘀𝗶𝗻𝗴 𝗮 𝗴𝗿𝗼𝘂𝗻𝗱 𝗳𝗮𝘂𝗹𝘁
Here are a few more things that may help. Here are 4 pages out of the newest version of the Amel Book
Here is a Video for Disassembly of the motor: https://youtu.be/CczwUotFnSE
My conclusion based on what you have said:
Saltwater has probably gotten into the Stator Winding and the Rotor (see below). It is possible that cleaning will solve the ground fault. It is important for every Amel owner to keep a watchful eye on the AC Pump. Your Amel, when new, was equipped with a Calpeda seawater pump for the Air Conditioning. It is a very well-made and long-lasting pump. The Calpeda pump, like almost other compatible brands, has an internal mechanical seal. Calpeda places a "Slinger Washer" on the shaft between the pump body and the motor that will hopefully sling leaking seawater away from the shaft and therefore keep it out of the motor. I have been on a number of Amels and found a telltale line of salt from the Slinger Washer (photo below). When the internal mechanical seal wears out, that Slinger Washer will only work for a short time, days maybe weeks before seawater enters the electric motor. The first signs of a problem will be slight wetness around the pump area, followed by a ground fault tripping the internal breaker on the side of the 220 panel and/or the breaker on the shore power pedestal in the marina. In the following photo (sorry about the quality) do you see the thin line of rust that is aligned with the opening to the Calpeda Slinger Washer?
Typical Calpeda Motor: