The inspectors upon whom shall fall the duty of assisting a voter shall render such assistance inside the voting booth by showing him how to mark his ballot in order to vote as he desires, or the inspector shall himself mark the ballot as directed by the voter, but no ballot shall be marked by the inspector from any written or printed list or slip furnished him by the voter or any other person. The inspector shall not suggest to the voter how he should vote, or in any manner attempt to influence him as to the marking of his ballot, nor allow any other person so to do: Provided, That the duties and restrictions with respect to inspectors as provided for in this section shall apply to and govern any person assisting the voter in the marking of his ballot, in accordance with the authorization in section 751 of this act.