Diswasher wasn't cleaning the dishs because the spray arms were clogged with calcium deposits.

Replacement of the arms is very simple, the bottom arm pulls out after turning it counter clockwise, no tool needed. The upper arms need the use of a nut driver or simlar tool to remove the hex screws holding them to the water supply tubes. The hardest part of the repair will be removing the top dish tray. This requires twisting the door slide end retainers outward to remove them and then the dish tray will slide out allowing easy removal of the arm. The top arm is mounted the body of unit.
This problem would not have occurred if there was an inline filter on the cold side to filter out calcium (whole house filter). Another way to have corrected this without the purchase of parts would be to run the dishwasher on the rinse cycle 3 or 4 times using 1 cup of lime away on each rinse and also by removing the arms and soaking the arms in a 50/50 solution of water and lime away for 24 hours. This will break down the calicum and enable the arms to be cleaned using a garden hose. New parts however save time and labor in cleaning the arms, however the main drain and supply lines to the arms still need the rinsing prior to replacing the new parts.