I had the bars not rotating in my now very old 2005 Bosch Excel 500mm width dishwasher.
There seemed to be quite a lot of flow if I opened the door quickly but the bars were in exactly the same place every time and the contents not cleaned properly regardless of cycle type. I cleaned the whole of the grey plastic water distribution system in the washer’s interior and the water input filter on the cold supply hose and even tipped the machine on its side which drained lots of foul water out. I don’t think the latter is a wise move so don’t try it but I was desperate and getting ready to buy a new one ! It still didn’t work.
Not having a GoPro with a light I could wash too(!) I shaped a piece of wood the size of the door catch (don’t this at home !) and carefully switched on. A 5ft spout of water shot out of the base (I had the filter and all the surrounding parts removed), soaked me and the worktop opposite as we have a galley kitchen. Nothing wrong with the pump then (!) so only reason is plumbing, but what ? Simple answer : The rear of the top rotating bar vertical supply pipe is not sealing to the distribution pipes in the top basket and loosing pressure to both top and bottom bars.
So stretch the top basket by treading on it and pulling so the door when closed pushes the basket back onto the pipework. Works as good as new !!!!!