2003 VW T4 Caravelle Carthago conversion with RnR bed.

Anyone know how to fold the headrests back for driving so I can see out of the rear window?

There seems to be a metal pole inside each headrest that drops down to allow them to fold back and goes up to hold them firm in place. I can't find a lever or button that drops the support pole down. One of the metal poles has dropped down of its own accord (over enthusiastic dog in the boot trying to see over the top) and I can't get it back up to make it rigid when in "bed" mode. 

The headrests are part of the bed and a cushion slots in the gap between them when in bed mode.