Originally Posted by
fastair
Thnx Richard, it is the truth though. They aren't doing a quick once over of the aircraft, it'll be out of service for a few days.
All smugness aside, it's hard to see how multi-day mx makes "late aircraft arrival" appropriate as the cause of the delay of the next leg, per the rest of OPs info.
(The rest of fastair's post had more relevant info, though. The ORD-MCO aircraft was not the BUF-ORD aircraft, it was some other aircraft, looks like UA868 LAS-ORD)