For some reason, this is not in the manual for my 2004 RX with 93k miles. This is my first change.
1. Remove 2 inch plastic cover where the arm attaches to the window.
2. Remove 10 mm nut.
3. Gently pry the arm off the shaft with a little leverage.
4. PROLINE is the only brand that had a model number for this car, PRV142.
5. The entire blade and frame snaps off the arm and the new part snaps in. I will post a video soon, but once the arm is off the job is much easier. If the blade is laying face down on a bench, the arm pulls UP.
6. Check the Proline instructions for help.