Finally managed to get the clamps to release. They were stiff from unuse, is my best guess.
Will be heading to Cairns to go out with Reef Encounters for about two weeks, then headed back to Syndey for a couple days. Going to try to go looking for leafy & weedy seadragons, as long as I'm in the area. I'm really looking forward to this trip, it's probably at the top of my bucket list.