To latch onto, tear into, hold fast, grip, or grasp as an object or concept.
1) Muckle on the end of that, and fetch it on up.
2) Johnson's body was a sight to see when they dragged it on up from the bay, with 5 great big lobstah muckled onto him.
3) Joe's wife was some steamed, why she muckled right onto him as he came through the door. Pert neah killed him, she did.