For a tired socket my first recommendation (and the immediate action on any amp I personally own) is to replace the socket.
If you feel strongly about not replacing the socket you can use a small dental pick to try to bend the pin contacts back into place. As usual, make sure the amp is de-energized and that all caps have been discharged. Note that bendings the pin contacts back doesn't always yield good results. It can also stress the metal resulting in another failure down the road.