&quot; 8.4.2. ensure that for each replacement disc and drum at least the tests prescribed in Annex 9 to this Regulation are carried out on a statistically controlled and random basis in accordance with a regular quality assurance procedure. &quot;
&quot; 8.4.2. ensure that for each replacement disc and drum at least the tests prescribed in Annex 9 to this Regulation are carried out on a statistically controlled and random basis in accordance with a regular quality assurance procedure. &quot;