Dear expert, my Bosch Logixx

Dear expert, my Bosch Logixx dishwasher which is 8 years old has stopped washing properly. It starts ok, it heats the water up ok, the door holding the tablet pops open ok. It seems to drain ok at the end. It seems to wash almost normally at the 70degrees wash but the 55-65 auto wash and the 50 degrees eco wash don't clean. Listening through the door as it were and opening the door now and then to see what is happening it seems to rinse at the start but then it seems to pause and make the normal quiet hum that it might make as it normally changes to a different bit of its programme but instead this goes on for ages ie it is not washing but the time still ticks down and when I open the door nothing is moving no water is spraying or at the bottom and there is a sucking noise. I normally run the programme on reduced time which has always been 98 minutes but I notice that this now starts at 84 minutes. It also sometimes sits at 1 minute for ages ie it never quite finishes its cycle. I tried the prewash cycle and the spray arm went round normally with a good jet of water as it does on the 70 degree cycle so I have cleaned and checked the filters which seem fine. I have taken the arms off and they have no blocked holes. When you cancel a cycle it drains fine. I hope I have given you some ideas as to what might be wrong. I am grateful for your advice. King regards Sandra