Des Higgins wrote:
How do you get the plunger base (the bit at the bottom of the tube that
moves when pushed) out?

Des,
I used a long Chop Stick to push the plunger back before
refilling. It was quite a job and I did have to hit it with a 'mmer.
I've also got some long pieces of 6mm. dowel. Try a metal skewer.

Chris.