I have a BO that may have Marek's (unequal pupils, no other symptoms) setting on a clutch. I'd like to vaccinate for Marek's in ovo. Has anyone done this? I've read to insert needle in big end of egg 1 inch, but that sounds a little far. I was planning on doing this at 18 days, then sealing off the hole with a dab of wax. What gauge needle should I use? Is there a technique to keep the eggs from breaking when you insert the needle? Any advise would be appreciated. Thanks.