to reel off the test tape than in the case of the embodiment example shown in fig1 as the diameter of the supply spool 23 decreases the embodiment example shown in fig3 of a tape magazine 50 is formed to include a compensation mechanism that is loaded with a force that changes depending on the diameter of a tape spool of the storage unit tape magazine 50 has a rocking lever 51 on the inner wall of the holder 12 below the dividing wall 14 which is hinged on the inner wall around an axis 52 the free end of the rocking lever 43 is also provided with a rotating deflector roller 53 over which the test tape 30 is guided the rocking lever 51 also extends tangentially to the spool housing 21 and touches the spool housing 21 at a contact point that is not visible in the figure the compensation mechanism is formed by a rocker arm 54 that can rotate around an axis 55 is pivoted on the rocking lever 51 the free end of the rocker arm 54 is provided with a follower roller 56 which rests on the circumference of the supply spool 23 at a contact point 58 a pressure spring 57 which is pretensioned with a certain spring force f spring is braced against the dividing wall 14 and the rocker arm 54 such that this spring force is applied to the rocker arm 54 when the drive for the test tape 30 is actuated it has to.