Whew. A good ending to that story, then. The capacitor took one for the team; I'd thought you'd let the smoke out of something important.
This has happened twice in the last 25 years to my BBC B+128KB. The funny thing is that it just keeps on working. It's a really tough machine!
It will keep on working with a dead filter capacitor but you might get some weird things happening or interference because that capacitor is there to filter out transients on the mains line.
Sure, I did get a new capacitor each time. I got the diagnosis from Sprow: http://www.sprow.co.uk/