Thanks, L4L. I did manage to figure it out in the end. Obviously there was one more combo I hadn't tried.
It's always that way - as soon as I post, I figure it out. So whenever I'm stuck I tell myself not to ask for help just yet, because obviously I'll figure it out shortly. And then I don't, I give in and ask for help, go back to the game and faster than you can say, "dork," the answer comes to me.
Pokey, I am stumbling around at the point just after the basement level, so we're at about the same point.