Removing the brass cover plate and then the cover plate beneath I discovered the mechanism was sat in water and had probably been that way for years.
I decided the only way forward was to drill the box from the floor which took over 5 hours of continues drilling, eventually I removed the box to see the protrusions underneath the box and understood why it had been so difficult to remove from the floor. I then quickly removed two Yannedis supplied 400's that had their pins cut off, packed my tools away and grabbed a bag I was handed earlier which I found out contained two versions of later model Gibbons.
Leaving site at around 5.30pm I ran into the notorious London rush hour traffic, arriving home at 9.30pm, dirty and tired.
Today I started work on the Gibbons at 8.30 am, getting it back together at around 5.30am after fabricating a new leather seal, changing the broken springs, drilling out a few snapped screws and re-tapping the holes.
I benched tested the Gibbons and discovered the piston was only working for the last 20% of the swing, I will now strip the Gibbons on Wednesday to find the reason/s for the poor performance of the piston/Gibbons floor spring.