Thanks to everyone for their contributions. The rectifier is fried and it has two earth leads. A meccano and spaghetti job once I get the replacement. Everything on an M3W is exposed but given the nature of electrons and their destructive affinity for water the rectifier seems ill-sited.
Has anyone devised a protective shield for it? Beyond my skills but I know a man who can. Any designs? Any experience? The rectifier's finned top would indicate heat dispersion but a screen in front would still leave it pretty exposed but protected from the direct blast.
