The Famous Arca-Swiss Lock-up Fix
The Arca-Swiss B1 monoball has a well-deserved reputation as being the finest general purpose tripod head made. It locks more solidly, supports more weight yet weighs less itself than most anything else. For nature work, a ballhead offers the ultimate in flexibility and the B1's variable progressive friction control allows you to set the exact amount of tension needed for the load.
However, there is a dark side to the Arca-Swiss head: under unusual circumstances it can "freeze up," the ball locking tightly and defying your best efforts to unlock it. You could easily never encounter this problem, or you could find yourself faced with it someday when you are out in the field needing to rely on your tripod to get the shots you came for. I've only had it happen once. This is not a common problem by any means, but it is a real one. Don't let this problem deter you from buying a B1 ballhead either, but every B1 owner should certainly be familiar with how to remedy it.
The problem seems to be most common when the ball is tightened before being transported and probably results form the vibrations that occur in transport. So the first thing to do is to leave the ball somewhat loosened when you transport it (but keep the quick release knob tightened in transport as it can indeed come off which presents its own set of problems).
If your Arca-Swiss B1 does freeze up, the first thing to do is to stay calm and not panic. The problem is easily remedied and requires no tools to fix. Simply grab the main locking knob firmly and force-rotate it clockwise about an eighth of an inch. This seems backwards since you generally tighten the knob by turning clockwise, but this is precisely why you should learn this before you need it. No amount of force in the counter-clockwise direction will loosen the knob, yet it is surprisingly easy to unfreeze the knob when you force it clockwise. Once this is done, normal operation should be restored with no harm to the ballhead whatsoever, and you should be back in business in less than a minute.
I first learned about this problem and its fix from Bryan Geyer at Really Right Stuff. His catalog is a wealth of information even if you aren't in need of his excellent products. I am thankful that he takes the effort to publish it.
Update 9/10/2005 - A reader pointed out something I should add here. Even though the ball on your Arca-Swiss may not be locked up, the main knob may be. If The same fix outlined here should still work though. I now shoot with a Markins head, but the Arca Swiss is still a good choice provided you know how to deal with this minor design quirk.
Update 4/15/2006 - Arca-Swiss now includes instructions with every head they sell on how to free up a locked ball. They recommend turning the main multifunction knob clockwise (tighter) slightly, then loosening then friction thumb screw, and finally loosening the main knob. In my experience, the thumb screw step was never really necessary, but if yours is being stuborn, gives it a try. Strange that Arca-Swiss still hasn't solved this problem though.