Campagnolo made a left hand thread crank remover for use on your cranks in lieu of the self-extracting sustem (or when it fails). It's been a while, so it might no longer be readily available, so if your favorite supplier doesn't have it PM me and I'll hook you up with one.

In the meantime put the crank bolt back, then grease the underside and threads of the removal ring (forgive me, I'm getting old and can't remember if there's also a washer between the bolt and ring, if so grease both sides) and install it into the arm tightening all the way to the left. The system should now be set to remove the crank when you back off the crank bolt, just as it did on the other side.