415p supervisor notified of strange sound at #3hoist. After investigating the noise it was determined to be coming from the grid coupler between gear box and drum. Evac started @430p out #1 shaft so the #3 coupler & grid could be inspected. MSHA Notified at 445p, all out by 545p. Grid was intact but contacting coupler case. Grid adjusted & hoist returned to operation @645p.