The drum in almost any dryer has to have a little room to move in and out as it rotates but sounds like yours is very sloppy. If you have not already taken the drum out you should do so and check the seal . It may have just worn out. Some of these are replaceable but must be glued in place. A new seal if available should come with instructions and hopefully contact cement to install it . I have done it and it takes quite a bit of patience and I usually use the old spring loaded clothes pins (it takes a lot of them) to hold the seal in place while the cement dries. Allow several hours of drying time.