I do the same, I wrap hemostats with teflon tape, they still pop off from time to time but overall it works. You need to do this or you can't push the rocker arm down enough to allow the half-rings to be installed.I'd like to echo this comment with another pointer. It helps to be able to hold the valve from sliding into the head even if at TDC. In the past I've fashioned a hemostat with bent ends and electrical tape on the ends to prevent marring. It looks like EMS now has a 7mm plier for this purpose. Currently out of stock, I'll be buying pair of these for the next desmo service.