If the jack is shifted or loose it could be the port inside had been damaged or broken. If your charger works for awhile and then shuts off, it is either a loose connection as you mentioned or you might be using the wrong one. Microworx can help you find a proper AC adapter. Test your power port with one, and advise if your port itself is damaged. They have also helped me with repairs on damaged ports in the past. Hope this helps
How confident are you it's not the battery that has gone south? How long have you had it?
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