The 45w power adaptor on my 2010 13" Air died after about 16 months of use. It was acting flakey up to the failure, and finally the green or orange light would not come on. Went to apple store and bought a 60w adaptor, and it works fine. I've noticed a lot of failures on these, wonder if Apple is going to have a recall? The way it acted, it appears the capacitor slowly went bad. This could be a design flaw. Shouldn't have to shell out $60-80 for a new power adaptor after a year!
Apple has redesigned the magsafe three times now.
They KNOW they have a problem, and have settled class action suits over them. It is a design problem. Most issues you'll ever have with Apple is because they do trial and error designing of things. You know, like with their overheating iPads and glass iPhones.
The problem with power cords is that people drag them around everywhere, they let their pets get to them, and they go through lots of wear and tear. With laptops, you're not even supposed to be using them constantly, they're there for when you need to charge the thing, and leaving it on the machine constantly with ruin the battery.
I don't know if you've ever noticed it, but the thing is ALWAYS in use when you have it plugged in the machine, hot to the touch if you touch the charger's base. I personally think the reason why people have so many issues is because of that. 365 days of constant charging...
I had this happen on my first MacBook Pro too. My dad sliced the cord open and added some electrical tape at the tip. That worked for another year or so, constantly adding tape, but then it stopped working completely.
You should have taken it to Apple when it started doing that in the first place though.