Power Adapter Cord not charging new battery.

I have had my Samsung Galaxy Tab A only about a year now, but have had to replace it's power adapter cord twice in that time and am again replacing it today because it is just not charging my battery in the Tablet. I have had the tablet battery checked and it is good. I can wiggle the connection between the cord and the tablet around sometimes and get some juice out of it but I have to sit there and babysit it until it is done and can get nothing else done. I have asked about this before and nobody seems to be able to help me. I hope that you can. I am very frustrated. Power cords do not come cheap and neither is my time when I have to sit and babysit a machine to get it to work again. :( Please help if you can. I just do not understand. Thanks in advance.