b and the fulcrum a with a rotary head drum arrangement to the above described embodiment of the invention setting a head mounting for effecting pairing adjustment involves the steps described hereinbelow first a head angle r balance and the like as well as an amount of projection of each head beyond the surface 10 39 a are set then the head base member 15 39 is mounted on the surface 11 39 a of the drum base 11 39 of the head drum 10 39 via the mounting screw 14 39 head height adjustment pairing may be accomplished by suitably turning the pairing adjustment screws 17 39 17 34 for resiliently flexing the head mounting portions 15 39 b 15 34 b in the upward and downward directions about the fulcrums 11 39 g 11 34 g according to the movements of the head mounting portions 15 39 b 15 34 b the edges 16 39 a 16 34 a of the heads 16 39 16 34 are caused to move to vary the heights thereof as mentioned hereinabove with reference to fig2 in accordance with this invention the three points a b and c are established such that a distance d 1 between the leverage point c and the fulcrum a is longer than a distance d 2 between a controlled edge b and the fulcrum a thus a deflection l c occurring at the leverage point c is greater than a corresponding deflection l b of the controlled edge b that is l b lt l c accordingly a very fine adjustment of each head 16 39 or 16 34 for example of a few.