As you can imagine, I travel through Mordor Central with a bike fairly frequently. The vast majority of the time, the lifts are working fine.
It's the platform 6/7 lift that's the real bugger, though. That's the one that's on the natural route between the foyer and the subway, and when that one goes out of order (or is just backed up with confused people with prams and giant luggages[1]), the whole lot grinds to a halt, and it can take a good 20 minutes to escape.
[1] Inevitably heading for the Stansted or Reading trains.