I've just asked the same question, hadn't seen this. However, I pinched an o-ring and had the bike running. Since I've also pulled the head, can I reuse the gasket. The blue sealant around the pushrod tube holes and the upper studs has been slightly pulled off. Can I just smear a bit of sealant on there? Is it enough just to replace the damaged 0-ring, or will I need to replace the large o-ring as well. Sorry to ask the same questions again, but my bike has been running for a minute or two.
I just had to check what the problem was and didn't want to leave the head attached by two bolts over night. Are these o-rings special, or can I just get a generic one, of the same size?