I grafted to 30 JZ-BZ queen cups from my 100% VSH breeder queen purchased last Fall from Harbo Bee Company http://www.harbobeeco.com/breeder-queens/ . Grafting is hard. I have tried various grafting tools and so far the one I like the best is the inexpensive Chinese grafting tool. I have found that it works best if the tongue is a little wet so I dip it in water and wipe it off every other or every third graft. This seems to help the tongue more easily slide under the larvae or perhaps to wick the larvae onto the tongue. It also helps the larvae slide off the tongue into the cup. Before I figured this out I am sure I injured at least a third of the larvae I grafted.
A head mount magnifier with LED lamp makes seeing the larvae much easier. I was able to find larvae the same size or slightly larger than eggs. The wet tongue on the grafting tool hleped a lot with these small larvae since there is not much royal jelly in their cups yet. It is true that the wet tongue greatly dilutes the royal jelly but research has shown that all the royal jelly is removed from grafted cells and then refilled by the cell building bees, so as long as you get the cells into the cell builder fairly quickly it should not be a problem.
The top chamber above the closed cloak board is packed with bees with bearding bees at the entrance. I am hoping for much better results than my past use of a swarm box to start the cells and separate cell building colony. Tomorrow afternoon I will open the cloak board partly.