I have had a Gitzo GH2780QR head since October 2013. It has not been heavily used, and I have been very careful in handling it. So, in March 2014 I was not happy that the ball lock jammed, requiring me to send it for repair to the authorized Gitzo repair folks. It was repaired ("rebuilt" according to the repair document) quickly, under warranty. Now, in 2016 I am really annoyed that it has happened again. I'm not at all sure that I want to have it repaired a second time because I doubt that I would ever trust it again. However, before giving up I would be interested to know if others have had the same problem and, if so, if anyone has determined a way to avoid it.
Thanks for any insights!