Ian
I presume you have dropped the motor/gearbox unit and checked that the furler operates with the winch handle?
If you have also checked that the motor runs when disconnected from the gearbox, then the gearbox is the problem. If the motor does turn the gearbox then the gears have stripped. If it just jams, then the gearbox is seized. If either of these, get two new gearboxes, because the outhaul one will be in a similar condition.
I bought 2 Bonfiglios last year and replaced them both. They are a simple right angle gear drive.
Do have a look in the Amel Owners archives. There are photos of disassembly of both types of gearbox Amel used, but I believe they are not interchangeable. Alex (Nikimat) did a direct comparison of both Bonfiglio and Leroy Summers gearboxes to show the differences.
The furler gearbox is simple to change, although I did need a hydraulic press to get the drive shaft out of it. The outhaul gearbox removal was a bigger problem, and Amel Martinique removed the boom to take it to their workshop for removal.
The Bonfiglio gearbox comes filled with grease (sealed for life). Amel separated the one they fitted for me, cleaned it out and refilled it with hypoid 90 gearbox oil. There are discussion topics on grease v oil and the installation of grease nipples to renew whichever lubricant you decide on as a routine service item.

In UK I paid less than £200 for each gearbox. It seems they are readily obtainable. My suggestion would be to order two, even if you can free up the existing ones. And do follow the advice of other Amelians who have experienced the replacement process - take the Anderson line tender off the outhaul gearbox every year and regrease the shaft and woodruff key - otherwise even a sledgehammer won’t move it! (I watched Amel try!).

Good luck

Ian

Ocean Hobo SN96