727 seal leak
Gotta drop the valve body, pry out the old seal and press the new one in using a bolt/nut combo with a washer the same size as the seal to press it in evenly. A C clamp and washer will press it in, too. Not too bad a job to do even on the ground. Clean up the selector shaft and deburr it or you can nick the new seal. Hope this helps and if you need pics PM me.