I position the piston so that the crown is facing me. If you notice, there is a little divot cut out of the pin bore. Find yourself a little flat head screwdriver....the smaller the better. I then clock the wire lock so that the end of the lock is just past that little cut-out divot....so if the crown of the piston is toward you, the divot is at like 11:00 and the end of the wire lock is at like 12:00. You will be able to get most of the lock started in the groove by tilting the lock (basically getting the entire rounded portion down in the groove, with the ends of the lock sticking up out of the bore) then use your screwdriver with the tip in between the wire lock end and the little divot in the piston to basically compress the lock and get the rest of it down in the groove. It will click when it goes in.