I sent off my cracked M400 White Tortoise cap a few months back to Stone Marketing, who deal with Pelikan repairs in the UK.
Just wanted to let you all know what a great job they did - I received a brand new cap this morning, and Stone dealt with everything completely free of charge (I didn't buy the pen from them either).
I've missed using my White M400 so so much, am delighted to have it back, with a new cap and in time for the new academic term! hooray
Emma