Oooer.

So, one experience I read (amongst many) was someone modifying the AP2 board to remove the transformer as they could feed a local 12V DC straight into the onboard regulator on the AP2 PCB. They removed the transformer and inserted 2 pieces solid-strand wire from the two primary terminals to the two secondary terminals, then removed the 110VAC (this was an American site) input to the board and sourced 12V from "elsewhere". That fed into the local bridge and onto the local 7805 regulator. That could be a very easy fix for you if you want to avoid the cost of a new AP2.

Chances are its an embedded thermal fuse in the primary that's gone.

Very useful information and follow-up. Thanks.