Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, have you tried a cleaning disc for such purpose similar to the products shown HERE?
Then it would be an internal hardware issue.
Are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even perhaps a soldering iron?
Still, good luck and thank you too for the opportunity to be able to share the information.