Why is the top shelf of my Neff dishwasher not drying properly?

I have a Neff integrated dishwasher model no. S5409XOGB01. It has suddenly started to leave all items on the top shelf soaking wet with bottom ones not as dry as they could be (though this may be water dripping from the top items). The top and upper side casings in the machine also remain wet. Have tried everything - cleaned everything thoroughly, run cleaning programmes etc and nothing works. Can anyone help? If it helps I use Finish classic tablets, separate rinse aid and do not have to add salt as I live in a soft water area.