Chair part is stuck

So my Razer Iskur broke down and Razer sent me the replacement part. Unfortunately, i can’t even get to put the new part in because the base of the chair won’t dislodge from the cylinder. I’ve tried almost everything. In the instructions, they suggest hitting the base of the cylinder with a rubber mallet. My rubber mallet is already broken down. I am desperate. Thing is ABSOLUTELY stuck there. Any suggestions?

I already tried lubricating it with WD-40 in hopes of being easier but nothing happened.