The dishwasher wasn't washing properly, the rinse tube didn't meet the water supply.

I removed the screw that held the arm in place. Make sure you remember where it is supposed to go & keep the little clip that holds it to the top rack. Put the new parts in just the way the old ones came out. Don't forget to use the new screw & washer, my old one was a little stripped. Easy, just as the other posts said (and reading them gave me the confidence to try this myself!)