If you had a new drum fitted recently you may find this is a loose concrete weight.
What you need to do is remove the top and you will one of them there. Check the bolts are tight on there.
If that's ok then you need to check the front weight. To do this open the door and remove the outer door seal clamp and unlip the door seal.
Lean washer backwards against a wall so the drum drops backwards. Then you can check the front weight. Depending on the model the front bolts may be torx bolt (star shapped).
Make sure the bolts are tight and that should cure the fault. But from what you say im pretty sure you will find this is going to be loose weights.
If you need anymore info just get back to me.