I wrestle with the thing, dump a lot of lubricant oil on it. The legs jam.
One leg fell apart... I think I will buy Sirui. Think OP going to kill me, I unscrew all the screws still can't take out the bloody knn head off the centre column. Going to bring to them and ask what's going on.
Next time, you might want to grease it internally as well.... Before taking it for swimming.