Steering arm and Hynautic steering

[Vic]

This Mariner has a stainless steel steering arm that goes through the trim pivot on the motor bracket. I thought that it would come out. The steering is hynautic and the old owner told me that it was original. Their are two dogleg shaped cast parts on either side of the rod. I took the bolts off banged on them, went to the dealer, where he sold me a steering rod cleaning brush, and told me to buy a sacrificial nut to bang on, I've been banging on it but I cant get it out. Has anybody tryed this? I did a search but didnt find any threads?

I got the grease and the brush just let me at it.