Berger. My engine, XA7 280, had to be completely dis-assembled at 12K miles. Based on the reputation of the first 500, I assume it was lubrication. I found it dis-assembled right down to valve guide removal. Lubrication has to be pretty shitty to lose your valve guides at that mileage. I believe those banjo bolts can be had these days so if I've screwed up, I'll get a new set.
It's all an adventure.