#31 BSB Biomax Tibase is stuck: suggestions?

Authors
#31 BSB Biomax Implant was restored with Tibase Zn screw retained in 2017. Crown became lose, broke off at the attempt to remove obturation material from the access channel. The abutment screw was unscrewed and removed. Tibase is stuck. Cold welding? Tapped on the side, pulled . No luck. Any suggestions how to remove it? If cannot remove it would you try to make a new cementable Zn crown over Tibase by packing cord and taking the impression? Thank you for your help.