As far as I can remember, I actually did figure that out BITD, but, then again, maybe I tried anything & everything in the game till that worked? Or, maybe that sense of evil(or whatever it says when you walk in the basement) rung a bell in my head(har har) which gave me a clue of what I should do down there? It's been too long ago now to remember, as now I just know what to do when I play that part.