Spray holes clogged by hard water deposits

I took off old upper spray arm by gently prying it and the retainer off the upper section of the dishwasher. When I first did this, two prongs of the original retainer clip broke off so I had to order a new retainer clip. The new arm fit perfectly in place and was easily held in place by the new retainer clip. This is a very simple and easy repair. The only tool I used was a flat headed screwdriver to pry off the old arm, but one could probably pry it off manually also.