IInjector tip cracked off ISX 600P

[Viperizer]

Hi, I had cyl #3 injector tip brake off, simply cracked in half . A piece about the size of a popcorn kernel. bounced around in the chamber - piston doesn't look to bad, couple kiss marks... bore looks fine, valve faces look fine. I drove about 200 miles like this...coach ran fine, noticed smoking, otherwise no other issues. The broken off piece is not in the chamber, my questions are, what could have caused this to fail. I checked the filters, no water in them. I looked that exhaust side fan, I do not see damage, should I pull the turbo, take the housing off and make sure the piece is not in the housing?
Please note, the following - #6 intake valve failed on this engine at 48k miles, hell of a mess....I am not sure if the injector that broke was the injector that as in cylinder 6 when it exploded... it may have been??? Hoping someone can give me some input. I have pulled all the injectors, I do not see anything wrong with them.
Thank you for your help!!