Can you clarify whether you are want help removing gthe blade boss of advice on repairing a blade boss, as it would appear you are asking two different questions.
To make it easier for you I will answer both questions:
"how can I repair my mountfield sp470 blade boss ?" ANSWER: You don't. If it has been damaged and fractured or one of the blade locating lugs has sheared, then the boss has done its job and should be replaced. The blade boss is a deliberately manufactured "weak link" designed to prevent further, more serious damage to the engine.
"How do I remove the blade boss do I need a puller"
ANSWER: Gernerally a puller is not required, but will help if the boss is particularly tight. If it will not remove easily by simply puuling with both hands, then screw in the blade bolt, leaving a gap between the boss and the head of the bolt. With a hammer in one hand and the other pulling behind the blade boss, gently tap the head of the bolt until it releases. Then remove bolt and boss.
Pleasant, October 2011
