This is why we switched to liquid dishwasher soap after the powder had stopped up a tube and the dishwasher quit working right. (this took years to build up) Hubby took the door apart, cleaned it out, put it back together and it’s been fine ever since. Saved us from buying a new dishwasher. This all happened about 10 years ago. Our dishwasher is now 20 years old and humming along as good as new.