Ladies, I wonder if any of you can help. Our dishwasher has started to leave a residue on some of the dishes on the top shelf, notably glasses or bowls (not usually anything else), it always looks a bit like weetabix (even when no bowls with weetabix have gone in). We have cleaned the filter, filled up the salt and rinse-aid and really can't think of what else it might be. We also regularly run a dishwasher cleaner through it to keep the drains clear. Has anyone else had this problem and resolved it? Many thanks.