I have just finished removing the old clothes line which the tree loppers destroyed. Unfortunately it was an original hills hoist. The centre aluminium casting is smashed. The clothes line is incredibly over-engineered. 50mm main tube, 5mm wall thickness! The stringers that hold the arms up are 1/4" solid steel bar. The concrete block the base is set in presented a big problem. The slab is approx 400mm wide and 500mm deep. I actually bent the box trolley transporting the thing.
To get the slab out I had to use a combination of leverage (framing pine - I bent a star picket using that), back-filling and a really big hammer.
First I dug around the edges about 200mm (one shovel width) on two sides after realising how huge the slab was. I dug under one corner and then sheared the corner off with a few solid hits of the hammer. The slab was unaffected by the hammer when it was encased in earth. Next I had to tip the slab over into the hole because there was no hope of moving it until I got rid of the "suction" effect the wet ground had on the slab. To raise it out of the ground I used leverage and back-filling. Once near ground level I was able to push it up and over the edge using two pieces of framing pine as levers.
Suprisingly the new clothes line only has a plastic insert to set into the slab. The insert is just 340mm deep!