That makes 2 of us, Neil. I thought I had broken mine as well until I figured out the mechanism. It took about 30 seconds before I figured it out (which I think is an embarrassingly long time)...

I am a big Zebra fan. Great value for the price and fantastic customer service too which completely surprised me.
I find this size pen a little too small for frequent use, but they are great for occasional or emergency use. They are so small that you can hide away a set almost anywhere without noticing them.
The Zebra telescoping and compact pens are also very nice. Both give you a full size pen in a small package.
Normally, I just carry the full-size Zebra G301 though.