ColinC,
the same happened mine, and they sent out the parts free of charge same as James said. I think it was the 'Anstechscheibe' (no.3 on the diagram James linked) on mine that was cracked, but they sent out a standad spare parts kit.
James,
if you've any spare parts you don't want (or nobody else wants either), I'll take em off you. I still use mine regularly.