Ok Bruce, I used a hardwood dowel as a punch- I gave it a few taps and the zinc retainer came out easy as pie! The backside of the retainer against the flywheel was covered in oil. I am assuming that this indicates a seal failure at the mating surface of the block and the zinc retainer. I will clean this surface somehow and reseal on reassembly. Do you have any suggestions for the sealant needed?
Thanks again,
Laurus