I tried cleaning them with alcohol. It's pretty clean. I have read that the battery management can drain the battery to a level where it won't charge unless you use a newer style charger. Pretty upset with the quality, < 2 years old. Not to mention that they don't repair only trade out for $320.....
This is the one I have , says it's 2A - Amazon Link - http://www.amazon.com/Adapter-Micro...7&sr=1-3&keywords=microsoft+surface+2+charger
This is the Surface Pro 2 charger, ad says it is 3.6A output - http://www.amazon.com/100-240V-Charger-Adapter-Microsoft-Surface/dp/B00C6WSXTA
It was another thread that mentioned this. I have been scouring the internet for someone to repair this one but for $12.85 this might be worth a try. I'll see if I can find the reference thread.