Check/clean your vent system.
Check the rear drum support rollers for slop/wear. I would but a drop of oil on the shafts. Just a drop as oil will collect lint.
Check the front drum glides for wear.
Check the idler wheel for slop. Also a drop of oil.
Check the drum seals.
Check/clean the blower wheel.
Often things can get coated with softener residue so check/clean the air entrance holes at the back of the drum. Also the lint screen, sometimes it has to be washed with soap and water.
Check the motor armature for slop. Again a drop of oil would not hurt.