With 8 or 9 hours of time difference a lot has happened since I went to sleep! Last night I had got as far as realising that U1724A was sinking current at its output so was not going to be responsible for excessive current drain. Overnight I remembered that it was part of a dual op-amp so I got up early to check what U1724B might be doing and found, not surprisingly, that Harvey had got there before me.
I hope you are now on the home run.
Roger
