there has been a loose board on the lower deck for quite some time now, which has tried to trip people up for ages…
it was a bit warped and we had tried screwing it down at the two ends, but clearly the wood underneath was not in good condition in those spots… recently, the hose got stuck in it, lol…
finally, I lifted it right up and checked underneath only to discover that the screws in the middle were too short, so I brought out the drill and screwed in much longer ones…

and now it is no longer moving… yay me;-)…