Replace td head prechambers or not

[Familydiesel]

I have been rebuilding my 1.6 td, sent the head in to get it machined and rebuilt.  The rebuilder told me that the prechambers were cracked, but not too far to cause a problem.  They said I could run them since they had done others that were even worse than mine.  I have installed the head on the bock, but am now wondering if I should run them or remove the head, locate new ones (which is not too easy in itself), have a machinist either recess the head to fit the new chambers (with milled head) or install them and machine the new chambers down to the head surface. 
What would you suggest and/or what are your experiences that would help me here? 
Thanks,
Greg

[wolf_walker]

I have never seen new chambers, and never seen any not cracked.  I suspect you'll hear that a lot.
Apparently the combustion area in a VW diesel is just a brutal place to hang out, most stuff
ends up being pretty beat up looking after it's there for awhile.

[maxfax]

You should be fine with cracks in the chambers unless you're looking at trying to make some crazy wild donkied power.....   Were they peened in the head before you installed it??

[smutts]

That is not a crack, it is a stress relieving slot!