Bob Pulford was a tenacious penalty-killer and a relentless forechecker whose pesky forays drove hockey rivals mad. Gordie Howe called him “one of my private headaches.”Mr. Pulford, who has died at 89, was a hard-working, two-way player for the Toronto Maple Leafs dynasty of the 1960s, winning four Stanley Cups with the club. An opposing coach once called him “the backbone of the Maple Leafs.”