No fee charged for representation services rendered to a claimant
with respect to any claim under this part shall be valid unless
approved under this subpart. No contract or prior agreement for a fee
shall be valid. In cases where the obligation to pay the attorney's fee
is upon the claimant, the amount of the fee awarded may be made a lien
upon the benefits due under an award and the adjudication officer shall
fix, in the award approving the fee, such lien and the manner of
payment of the fee. Any representative who is not an attorney may be
awarded a fee for services under this subpart, except that no lien may
be imposed with respect to such representative's fee.