The appeals board and its representatives and administrative law judges are not bound by common law or statutory rules of evidence or by technical or formal rules of procedure but may conduct the hearings and appeals in such manner as to ascertain the substantial rights of the parties. A full and complete record shall be kept of all proceedings in connection with disputed claims. All testimony at any hearing held in this state upon a disputed claim arising under this division shall be recorded and, when feasible, by a reporter in shorthand or by machine writing. The testimony need not be transcribed unless the disputed claim is further
appealed.