As with most of Roger's puzzles, this one doesn't have a clear objective. I had a guess as to what I needed to do, but didn't have much luck getting anything to happen. I fiddled with it on and off for about two and a half years, picking it up every now and then, but didn't have any luck. The faucet twists around, the wing nuts screw up and down, and you can hear a distinct rattling when you shake it around, but nothing seemed to do anything!
After having been stuck on this one for about six months, I was particularly surprised by Oli's review stating that he'd solved it in a half-day! This, in addition to the fact that he said it had a good "a very satisfying 'Ah-Ha!' moment", re-inspired me to try it again. Unfortunately, again I came up short!
About a year and a half later, Allard also posted an interesting review that set me to working at it again. This time I was determined not to give up, and emailed Allard a few times to rule out a few things that I didn't want to attempt for fear of damaging the puzzle. This was fortunate, since none of them were correct! In the process, I got a slight nudge that got me thinking for a bit.
After a bit more puzzling, I finally had it figured out! Indeed, it does have a very satisfying 'Ah-Ha!' moment, just as Oli said! I don't really want to say much more, for fear of giving anything away, but it is a very well-done puzzle. I had a pretty good idea of how it would work, but lacked that one crucial detail in order to make it work. Overall, Wasserhahn is an excellent puzzle that I would definitely recommend if you can get your hands on one.
For more reviews of Roger's Wasserhahn check out Oli's review, Allard's review, and Jeff's Review.
For puzzling-inclined folks located anywhere in the vicinity of Rochester, NY (or willing to travel) there's a most excellent puzzle event coming up: The Third Annual Rochester Puzzle Picnic! It will be happening on the weekend of August 25, 2012. Jeff Aurand organizes the event and hosts it at his house each year, and it is a blast! The puzzling starts on Friday night and goes all weekend, complete with tasty food from Jeff's grill, good company, and plenty of puzzles! If you are interested in attending send an email to Jeff.