Just done my second round of grafting - first ever attempt was last month with a 25% take, which I was happy with. The first time I used a frame trap to confine the queen on an empty comb to obtain larvae of correct age. This time, knowing more what I was looking for, I just took a suitable frame from the hive containing my chosen breeder queen. However this was a fairly newly drawn frame and the wax was soft. The tongue of the Chinese grafting tool just kept going through the bottom of the cell, rather than curving round under the larvae. I got round this by breaking down the side wall of the chosen cell a little to approach the larva from a flatter angle. Was much more confident this time, taking my time, and will let you know the " take" in a day or two. Now I know why the experienced suggest using older comb to graft from.
Used Cloake board on both occasions, makes it a whole lot easier. Last week I had added frames of soon to emerge brood, so the hive was crammed with bees. Not much pollen in any hives, but I did manage to find two good frames to put in the rearer colony.