grounding old work plastic box to BX
While swapping out a bathroom wall mount fixture, I see there's a plastic, round "old work" box that was used with the BX cable. Any advice on an easy way to ground the fixture without getting too involved with redoing everything? If I were to temporarily remove the box, I could reach the cable. Could I wrap/clamp some extra copper to the BX so I have something to connect with the fixture ground wire when the box is reinstalled? Thanks.