Use the rubber mallet to encourage the end cap off. 


 
Or use the cold chisel again to separate the end cap from the tube.
Use gentle taps and it will come apart.


 
As it begins to come out a bit more, change the angle of the 
chisel so it drives the cap out of the tube.


 
One way or the other gets results.


 
Now to remove the tube.  Use the block of wood and a large
hammer.

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