I can open these locks really easily. Apply torque, mash the inside with pretty much any pick, and it comes loose and turns 180° to the unlocked position.
What I can't do is lock them back up again. Nothing I seem to do makes even a single wafer set, and none of them seem to bind. To lock it, I must reassemble it by hand in the locked position.
The one in my own drawer in the office does have a key, and I can't re-lock it either.
Does anybody have any advice? I took some photos. Please excuse the poor photography; I had to light it with a torch and a flash, and shiny things can be hard to get right with a flash.
Here's the entire lock, intact in my vice. It's on its side (the top is to the left) and is in the locked position.

Here it is with the cam removed and the plug out. The wafers protrude by the same amount; this lock requires that all the wafers are moved by the same amount, which makes picking very easy indeed:

The plug, showing the wafers that engage the barrel when there's no key. The springs are to the left of the wafers, and it's the left side of the wafers that must bind to pick it back into the locked position. The right hand edges bind well, making unlocking it very easy.

A glimpse down the keyway:

Finally, a look down the inside of the barrel, and at the back of the plug:

It would be much harder to pick these locks open if they turned the mechanism upside down.
Here is an album of the photos. As with virtually every photograph I post online, these are licensed under the Creative Commons Attribution Share-Alike license.