How can I fix my GE tumble dryer model DDE7109VMLWH?

When I turn it on it makes a metal on metal sound. Seems to be making contact at the bottom of the dryer as the drum turns. I can manipulate the drum as if changing the balance of it by pushing on the drum itself. When I do that the noise goes away for some of the drying time but ultimatley returns. I don't know how to rebalance it or tighten it up. Can someone please help me? Thank you