The 1/4" hole at the top rear of the handle (#8 on page 20 of the manual). Use it gently. Mine failed (actually broke, not stripped). I've only used it to hold a SmallHD DP4 monitor, about a pound. Sent it into Canon for repair and was told by the rep that several of these are failing, especially rental houses sending them in. But they will not fix it under warranty, they wanted to replace my entire handle to the tune of about $600. The part looks like it's only held in by 4 easily replaceable phillips screws but I was told that's just a cover plate and the actual mount needs to be extracted from the handle by disassembling it, which apparently they didn't want to do, so the only option is to buy the new handle. I went up the ladder of supervisors at Canon and still got no joy. I got the impression this is an engineering screwup Canon will just remain tight lipped and stodgy about. It's too bad, using a small monitor in that spot is pretty sweet, I'll have to figure something else out.
![20130809_150614[1].jpg 20130809_150614[1].jpg](https://www.dvxuser.com/data/attachments/68/68129-252a87e9af7ea4f88fc0c9d0611180ca.jpg?hash=JSqH6a9-pP)