Save yourself the frustration
and unscrew the base from the deck. Then take the pedestal and base and throw them in the trash. 3/4" pin bases and pedestals are about $30. If you want to mess with the old ones, you can ussually pound out the pedestal from the bottom. Heat it up first with a torch and support the predestal in a vise or on blocks. Has to be on of the worst products they ever made.