If the heads are new, you may need to break them in. All you do is tighten them(the proper way, not in a circle, google it) evenly, and push in the center with the ball of your hand. If you hear a cracking sound, that's good, it's the glue breaking. Keep doing this until it mostly stops cracking. If they are not new, then you could try getting some Moongels.
Buy RTOM Moongel Dampening Gels | Dampening Rings | Musician's Friend
Hope it helps! Happy new year!
