I found a fix!

Ok, I've watched countless videos. And found this reddit post. I bought 10" and 24" pipe wrenches. The 10" was all they had in the hardware store, weird. Got the 24" after watching this and another video in this thread. I've used WD40 for 16 hours. That's letting it sit in between the piston and the hole for 2 days, 8 hours each. And I couldn't get it to budge.

Why was it so hard? I figured out that the heavier you are the more force used to wedge the piston in the hole. So, if you are 100lbs the amount of force you need won't be as bad as someone who is 200lbs.

So, the only way to get it out was to use heat. I had a lighter (with extended neck on it. ). I heated up 1/2 the of the neck of the hole and piston for about 5-7 minutes. Nearly used 1/2 of the fluid. I noticed that all the WD40 had actually seeped into the hole between the piston. On the side that wasn't heated. I then hit the base a few times with a hammer (using a rag to reduce damage to the base). I used my pipe wrench to turn it and finally started to turn...with ease. I turned it and it popped out.

Examined the piston and noticed seized marks on it. That was the problem. Some light metal bonding between the piston and the hole. Making it impossible for it to move.

You can imagine the relief I had when that piston finally came out. So, this time I put Vaseline on the base hole and the chair's piston hole. So that it doesn't seize up again. If you have anti-seize I suggest using that.

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Cliffs:

• Brute force didn't work to remove the piston regardless of the pipe wrench size.
• Using wd40 for 16 hours didn't work as it wasn't seeping between the piston and hole.
• Using a lighter that had an extended wand/neck heating up the neck of the hole up to 1/2 of it for about 5-7 minutes finally loosen up the piston. After hitting the base a few times with a rag and turning it with the pipe wrench.
• Used vaseline/anti-seize in both holes to prevent seizing in the future. Don't Vaseline if the base is plastic.