MacBook Air needs a new power brick. There are pins on springs inside the Magsafe thingie abd one of those is stuck down, so it can't participate in a charging circuit. The Magsafe connection is reversible, so it can still charge. Of course, this is the "L" shaped connection and the dud pin means it can only charge when fitted so the cable obscures the adjacent USB port.
Not happy. Not paying $129 for a new one (they used to be $79). It's eBay to the rescue. There's some in Sydney doing for $40 including delivery.
Sold.