Just one final loose end. Is 5ac supposed to be a "paired" answer? I suppose it is, though it doesn't really mean much to me. By my reckoning, that makes 18 paired answers, not 17.
I'm stuck on 1a, 12a, 14a, 17a and 23a. I can guess what most of these might be, purely because nothing else will fit, but I can't work out what the "other halves" might be. Any pointers?