Sorry! When I initially responded I didn't notice the web URL in your signature, which would have clued me in to your location.
This could be a lubrication issue but I would definitely check with an Arca rep as Nancy suggests. My squeaking clamp turned out to be a more serious problem than lack of lubrication. My first inclination was to lubricate it but when I inquired about what type of lube to use and where to apply it, I was told that certain types of problems with the tightening mechanism can lead to a total failure of the clamp. So, I'm glad that I got some expert advice as you are trying to do here. Sorry I can't offer anything more definitive to help out.
Also depending on the year of manufacture, your ball head clamp may not have been attached using the strong thread-locking adhesive. This may be worth checking into as well...
Good luck!