If it's hot water or mineral deposits. You can use Apple Vinegar and spray it on the areas. It might take a while and keep spraying it. It will take off all the old minerals and make it shine. Also great for taking off finger prints when diluted with water and used in spray bottle. I use to clean homes and it was safe for the environment too.
There are dishwasher cleaners that you just stick in the machine and run it. It worked on the lime deposits quite well on my dishwasher. Said it was septic safe, too. You just have to look with the dishwasher detergent.