"oh my wiring is acting up, and my fusebox is getting damp" That's your windscreen seal/sunroof drains/bulkhead grommets mate. Guaranteed. Except when it isn't. Feckin holes around the bonnet pull cable entry. This will be fun..
In the immortal words of the 80s band, Hot Chocolate. "it started with a kiss, never thought it'd come to this..." A kiss of a stone, in this instance I'd wager. Most here are familiar with the seriously tough underseal on the bottom of a mk1/mk2, especially around the rear, and the spare wheel well. As the pics show, it's scary what can lie beneath it! First pics, the rear bracket for the fuel tank straps. And here, just a tiny little dent, barely seen, to the side of the spare wheel tub.