U want my two cents? Ask Customer to make up about 2 fluid ounce measuring cup of Arm and Hammer Baking Soda and pre-desolve in a town and after the dishwasher has started and done its first flush add the backing soda water solution. Ask Customer to also put on table spoon of baking soda in the soap dispenser. Have them run the machine on long wash and let it sit a few hours. Then run again on long wash. Then go back and this time use Nickel Safe Ice Machine Cleaner in the machine adding pre diluted 4 ounces in 1 pint water, again adding after first water dump medium run time. Then ask customer to (unless you want to sit there for a while) to add 2 tables spoons baking soda to the soap dispenser and run the machine for another medium cycle.
If you smell any mold I would then use 3 Tablespoons of Bleach to the machine and run for a short wash.
Let me known how it works out.
I presume you removed any visible grease, mold or mildew also. Please advise.