Thanks Hy, that's v helpful. I'll try that on the reverse DEC setting out of curiosity (I don't think I need to b/c when I've played w that in the past - out of sheer ignorance! - it's not been good; my mount is an HEQ5Pro).
Yes, I did look at the log the next day & wish it had kept trying (I'm still puzzled about what could have happened - the main scope with narrow FOV found & aligned fine, so I'd have thought that the guide scope with a much larger FOV would be less susceptible to a freak cloud since it would need to be a much bigger cloud which would also interfere with the primary scope; M81 was pretty much near the zenith at that time, so no way any trees or roof lines could have been a factor. A mystery).
On the keeping-trying aspect side of Scheduler, I didn't realise that was a one-time rule that it only tries at that time. The reason I set a time was b/c I was in the middle of an imaging run which was centred on empty space to get a particular framing. And so I just thought I'd set a time to switch to M81, b/c I couldn't figure out how to se the earlier target as a Scheduler run (the Scheduler seems to require a specified target, vs the ability to either put in specific co-ordinates, or put a load-and-solve file as the target - unless I'm missing something. If Scheduler could be set up to not need a named target that would be great b/c then I could do these all as Scheduler runs and w the Terrain tool also up & running, hopefully it would figure out by itself when to switch targets)?
Anyway, thanks for the pointers on the guide calibration - much appreciated.