Great news! I'm glad it worked!So to update: she's spent two nights in the crate and this morning I let her out to stretch her wings and she is happily free ranging with the others. Thank goodness! She's still doing little broody clucks now and then but showing no interest in running back to the nesting boxes.
Thanks for all the advice. Next time we have a broody we'll do the 24/7 thing, it definitely seems to work quicker.