hole 21 of the substrate 1 so that the second male screw 27 is engaged with the second female screw 9 of the rotation head cylinder 2 a second coil spring 14 b interposed between a head of the second attaching screw 25 and the substrate 1 loads the second attaching screw 25 in such a direction to pressure contact the rotation cylinder 2 to the substrate 1 generally in a magnetic recording and reproduction apparatus the rotation head cylinder needs to be positioned relative to the substrate in a predetermined position with a high level of precision so as to provide reliable operation of the apparatus the dv digital video standards are provided for magnetic recording and reproduction apparatuses of systems in which a rotatable head disposed on a rotation head cylinder helically scans a magnetic tape according to the dv standards a magnetic tape having a width of 6 35 mm is wound around a rotation head cylinder having a diameter of 21 7 mm over 174 degrees the rotation head cylinder is inclined at 9 15 degrees with respect to the substrate when the rotation head cylinder rotates at 9000 rev min and the magnetic tape runs at a speed of 18 83 mm sec so as to record reproduce a signal to from the magnetic tape the linearity of the running locus of a.