In the manufacturing process, burrs are formed between surfaces. These burrs cut the O-rings if you are not real carefull at assembly.
On the kits I pre-assembled, I used an exacto blade to first cut the burr off then polished the holes for the injectors using a hand drill and green Scotchbrite.I think on some of them I even lubed the holes with Vaseline. I know I did on all of the ones I assembled and installed. To date no problems I've heard of.
No Adam, I'm not able to comment yet, litigation pending. When able I will share all with you all.
John