<p>A preload unit has a compressed coil spring (270) that forces a stationary drum (220) against a first bearing (250) to preload the first bearing and a second bearing (260). The first bearing and the second bearing connect a rotary drum (210) to a shaft (240). Independent claims are also included for the following: (a) a head drum assembly assembling method; (b) a bearing preload applying method; and (c) a assembly fabrication.</p>
