I have an earthquake 5020 rear tine tiller with leaking seals on the tine shaft.How do I replace them without distroying them in the process?

Hi,
Normally a screwdriver will pry it out. If it already leaks, what is the worry. The gearboxes are cast iron. Both use part# 1506 seal. The machine is made by Ardisam and mauals are here:
http://www.getearthquake.com/foundat...?type=category
Peace,
Clarke