| Ah, I was right. It happened on my front cylinder too, and made a hell of a racket. At least it is the front - you don't need to drop the engine. It's not too difficult a job to strip down the head, but you might need a new cam shaft, depending on how chewed up the end is. If your luck's in it'll be just a new woodruff key. But you'll deffo have to replace the pulley nut - they're single use only, and need a special tool to loosen and torque up. I got a bloke to make one for me. Or you could just take the head to your dealer and ask the mechanic to loosen/tighten them for the price of a pint. The valve gear's probably ok. | 
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