I should have been more specific as those bolts have been removed already, but I just wanted more info on getting a purchase on the centre-tube. If I punch it out, being thin-walled and threaded it'll be destroyed, which is something I want to avoid.
There is a blanking piece in the bottom of the column. Don't ask me how I discovered that! Take care.
A bit of heat may help you. It usually does.
Health & Safety personnel look away now.
When I disassembled my plungers, after removing that column I just levered the assembly out of the frame with a tyre lever. The thing shot out and bits flew around the shed. It's was very lucky that non of the bits came my way! On the other side I did the same thing but tied a rope through the hole where the column normally goes. This kept bits together on the hoist. Still quite exciting though! Just be careful with loaded springs.
When I reassembled the plungers I made up a piece of thread rod with large roofers washers which worked great except at the end while getting the large washers out from between the frame and the spring shrouds I scratched the new paintwork on the shrouds!
Last year I decided to do something about the scratches. When reassembling I strapped the bike down and used my hydraulic car trolley jack to compress the assemblies enough to just slide them into position. No damage done to the paintwork, or me.
Here's the thread:
https://goo.gl/YH3Ymi