My first attempt to cork my wine bottles resulted in a lot of shredded
corks.

I have an "Itallian wing corker" with 2 levers and a tapered channel - with
a metal plunger that pushes the cork into the bottle.

I am using #9 1 3/4' "super corks" that I soaked in water for a few hours.
I put them in the corker, set the corker on the bottle and bring the wings
down. I've tried it fast and slow. What seems to happen is the top of the
cork rips in a ring. Sometimes the lower portion of the cork gets messed up
as well.

I also tried it with a dry cork with the same result. Finally, I tried an
Altec cork with the same result.

Is there a technique with using this corker, or is this particular corker
prone to this problem?