Yes, you can squeeze the cheeks together, also you can take out the pin & put a new piece of plastic tube over it (can just be seen on your photo). Never lube the slidy bits or the plastic tube on the pin or it completely defeats the hold open grip
In the automotive equivalent of "have you tried turning your computer off and back on again", I took the entire assembly apart, squeezed the cheeks, slightly increased the détente (that's the name I believe for the little sticky-in bit where it was hit with a punch), cleaned everything, unlubricated everything. Result: nada, diddly squat, same problem. Solution: don't park on a hill or in a prevailing wind.
