hmmm thought there was a special part you could get. I have done them in the past with a deep 17 socket but didnt have the insert so i unscrewed them and had to pull them out with a pair of swan necks. Very difficult to say the least and I'm sure I damaged my new sparks when putting them in cos i sort of lowered them into the head and then dropped them in their holes. Lol Cant find the socket I used to use and the problem I'm having is that all the sockets that are the right size, won't fit in the head recess.