Help our dishwasher is siphoning back from liquids poured into the sink. I have run dishwasher cleaners through it, all washes are on maximum temperature 70 degrees. Both the sink and half sink have had drain un-blockers applied overnight and then flushed with a lot of boiling water from kettles. Anyone any ideas why this has suddenly started happening please. Plumbing has not been touched since this machine was put in some years ago, it is pumping out as expected at the end of the cycle.
Many many thanks in advance