Ok for one thing you are using way to much detergent you have soft water so your not suppose to use a whole bunch actually your only suppose to use 1 tablespoon per load,if you had hard water then yes you would use alot more. Since you mentioned that its getting worse its because all that detergent that isnt desolving is getting caked up in to some of the parts, Try using this product called DISHWASHER MAGIC, its a really good cleaner.
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Here you go click on the link below and hopefully there is a store near you.