I've been having a problem with the lightning port on my iPhone 5s. For the last year or so, I have observed that the connection isn't stable. my phone will not charge unless I move the cable around a little bit or it will stop charging if I jostle the cable. I also feel some resistance when I try to push the connector into the port. I'm thinking the port is either wearing out or has some crud stuck in it. I've had the phone for nearly four and a half years now. What would you guys recommend using to clean the port?