Manitou Magnum rebound adjust dial missing

bought a second hand Stache, noticed the rebound adjust dial was missing but being unfamiliar with Manitou just assumed it was a hex key job like with Rockshox. on closer inspection, it's a screw in dial. before i go shoving random things in there to bodge being able to adjust the thing, anyone know what might work or where in the UK i can get a replacement dial?