Dishwasher racks have become supremely adjustable and very complex; customers rarely use any the wonderful features provided. The only time a customer complains is if a rack falls loose or scrapes the door. Usually, these are an easy fix once you get a good look. Broken rollers are common. Loose rack mounting bolts can cause hard to find leaks that run down the outside of the dishwasher.
Kitchean Aid Rack with New Rollers
However, many upper racks include a spray arm assembly and damage there can cause poor cleaning. A broken upper arm will drop the overall water pressure. The rear connection point is also suspect; it must make a good seal or cause a loss of water pressure. A helpful trick is to set the upper and lower arm in alignment with each other or the door and test the dishwasher. If the upper arm fails to move, you have pressure problems. Find the damage, the leak or the pump obstruction. If you are brave, jerk open the door while the unit is running, see what is moving and how much water is flying around. An umbrella is helpful.
Upper Spray Arm Water Supply Tube
Customers often ask about replacing rusty racks but never buy when they find out that racks cost over $100. I give them the phone number to my supply house rather than have them think I am ripping them off.
Kitchen Aid Upper Rack