Remove rocker shaft and take out push rod you have to take out tube sometimes they are hard to get to move you might have to usee vise grips on tubes and bang up with hammer to remove the oring is only on the top of the tube try not to damage tube or you will have to install new tubes.what happens is the o rings get hard from the heat of the head over years and leak oil outside on the motor. if you don't damage the tubes you can just replace the o rings take them off and buy a hyd o ring kit and match them up or you can order them from a yale or hyster dealer the motor is a Mazda Va. hope l was of help.