I just bought one of these that was NOS but said it didn't work.
Fix was relatively easy.
1. I'm assuming there was crappy fuel, needed bled, etc, so I bled it and filled w premium butane.
2. Cleaned the nozzle w alcohol and even used butane to spray down it to make sure it was clear (originally seemed a bit clogged)
3. Got it to light, but intermittently. Discovered that it was sparking too low to consistently light, so all it needed was for that little wire that the spark shoots from to be pushed up a bit, and it was fine after that.
I also think that there is a slight design flaw here in that there's only two slots to allow oxygen in/excess butane to escape, which can cause problems.
AKA: You can't have the lighter set to nuclear level flame or it just doesn't work well.
Since this was the one of the first Google searches to come up when I initially started looking for help myself maybe this will help someone else.
Model is supposedly the "Elfriede" and my paperwork in the original box calls it a Series 20.