My MacBook will only charge when I apply pressure, what's wrong with it?

It's not charging alone. The only way my MacBook pro will charge is when I apply pressure to the charger on the port. Temporarily, I've been putting a rubber band around the computer and charger to keep it charging overnight, but I can't do that forever. It does look a little dirty in the port and I notice a tong in the charger had a little ring around it-which I cleaned off-and was silver(It was dirty and no longer gold). I do have a store near me that specifically fixes apple products, but I would like to see if there's something I can do in case they charge for a diagnosis or whatever. If you have a solution, let me know and if you have the same issue, let me know in case I do go to that store and find out what to do. Thank you.