Tabac Shaving Stick - How Does It Work?

I bought one of these shaving sticks from VSHOD.com a while back, and really like it - works great.
However once you've used the part sticking out the top, there seems no way to twist or push it up it to get the rest of the soap out.

I Googled it and also asked VSHOD, the guy there didn't even know, but was kind enough to offer me a new stick at the cost of a refill.
I'm now using the 2nd stick, and today I just grabbed a butter knife and pulled out the other 3/4 of the old stick, put it in a glass bowl, melted it in the microwave then formed it into a small cylinder and wrapped it in foil so in a few days I can use the rest of it.

Is there a trick to these things? There seems to be no mention at all online of anyone having this issue, just wondering if anyone out there has used it and if there's some kind of trick I am missing?