So: I sat and thought about the book, and it seemed to me that there were real problems with the main character: that he hadn't developed into a big enough/interesting enough character to carry the story.
Time for desperate measures: print it out and give it to my wife to read. I say desperate, because this is a tough moment for both the writer and the reader, made much more tough if that reader is also spouse. Too harsh a commentary and it'll send me straight to the office in a frenzy of words and storylines as I struggle to make the story work. Too bland 'oh it's wonderful darling' and I'll be left with nothing to work on and just as stumped as I am now.
What I'm looking for is a strange blend of support, encouragement, insightful input: and thank god, my wife came up trumps. She ticked the good bits. Noted the paragraphs where the story stalls for a moment. And when i asked her about the journey of the main character and my concerns, we worked out that part of his emotional journey was missing, and identified the point in the narrative where he could think and work out some of the challenges facing him.
I say all this, because yesterday (monday) i worked on the notes from that saturday night reading, and only added about 500 words: but it is startling how differently those 500 words make the story read. But it might have just been 50 or 100 words.
Readers pick things up as subtle as body language, as unspoken as feelings. Many writers make the mistake of not trusting their readers: and readers can smell an unconfident writer in the same way that dogs smell fear.