The right hand (looking from the top) of the pair of escalators closest to the western gateline at Canary Wharf (Jubilee) has been out of action for months (I think since about February). Sometimes there is a notice stating that it is out of service in the evening peak (I can't speak for the morning peak, but it doesn't seem to be in service at any time during the day) as due to a fault it can only operate in up mode. The poster notes that it is hoped to be fixed "later in the year" but it's already rather later in the year than when the poster was produced.
Any ideas what the problem is and why it's taking so long to rectify?
The essential things in life are seen not with the eyes, but with the heart. --Antoine de St. Exupery
I don't think it is "broken" at all. However it is the one that everyone goes down and causes havoc at the bottom during evening rush hours as people queue for the Westbound PEDs immediately at the bottom of that escalator. After closing this escalator the spread of passengers is considerably more spread out throughout the platform.
So I think this is a strategic failure that is (actually) working out well.