aha, perhaps i have just not been patient enough -- i plugged it in & got it started around 6pm last night, and had assumed it would warm up fully overnight -- and just checked again, now the temp is at 85.5°, so i'll just give it some more time. not much else i can do at this point anyway!
and thanks for the sympathies re: Maggie, she was a sweet (though timid) girl and a wonderfully reliable layer. i feel so torn in two directions, as i'm SO excited about the marans eggs hatching (each SPPR broody has one chick out already -- one has three eggs, the other has seven) at the same time!
While patiently waiting, see if you can verify the accuracy of the thermometer and maybe find a new digital one that reads tenths.
I use a brinsea spot check but those have to be shipped.