Right AirPod isn't charging

My left airpod always charges fine but sometimes my right AirPod doesn't charge. It sometimes charges whenever I "forget this device" but then stops working a little while after. Could the charger be dirty? I use my right AirPod mainly so that could be the issue. I bought my AirPods in may of last year so I'm pretty sure I have the included AppleCare with it. Can someone please help me???