[Johnb]

Can you not try and drive the broken bolt out the knuckle.
Common problem for the upper pinch bolt to seize in the knuckle. Usually end up snapping the head of the bolt off.
Been there done it but with a bit of heat and an air chisel I managed to get it out.
Not the nicest of jobs as access is limited too.

Cheers.

 

[Johnb]

Oh no, mine actually got a tiny hairline crack on one of the clamps on the casting. It didnt go all the way through. Will keep an eye on it to make sure it doesnt get any worse. Been ok for 7 months or so.