Have never been able to get the High Voltage Transformer off Crock. However, he does always seem to have a Voltage Amplifier on him.. which ain't the same thing, nope, uh-nuh already, tho it does share the word 'voltage'.
I've searched Mt Gigas thoroughly also and haven't found the electric eye or the transformer there. One other gadget component that is mighty elusive is the Demon Doll supposedly in the Upper Rapax Castle. It isn't the same gadget as the Doll found in the abandoned house in Arnika unfortunately.