take top cambelt cover off,take rocker cover off,then remove all spark plugs!get numbers 1&4 to tdc!doudle check buy carefully putting a long screwdriver down plug number one and slowly turn engine over until the screwdriver reaches its highest point!then remove the 13mm nuts from the rocker arms on cylinders 1&4 remove rockers the place tool where rocker was and screw down until you can get the valve collets(sp) out with a magnet remove tool,valve spring then remove seal,refit new seal and fit in reverse of fitting!do all 4 on num 1&4 refit rockers and fit new 13mm nuts (they are cheap!)and torque down!then get pistons 2&3 too tdc and do all again!