(a) Upon receipt of written notice from the Health and Safety District Manager of the time and place at which a field approval investigation will be conducted with respect to any machine, the applicant will prepare the machine for inspection in the following manner:   (1) The machine shall be in fresh air out by the last open crosscut and free from obstructions, or, if the machine is located on the surface, moved to a clear area;   (2) All enclosure covers shall be removed;   (3) The flanges and interior of each enclosure, including the cover, shall be cleaned thoroughly;   (4) All hoses, cables, cord, and conveyor belts shall be wiped clean to expose surface markings;   (5) All electrical components shall be cleaned to reveal all stampings, identification plates, certification numbers, or explosion test markings.