The new wiper arm looked ok and had a good sweep across the screen. However the spring behind the arm put a lot of pressure on the blade and was straining the Lucas motor. The original arm has a piece of spring steel on a cam set up to put tension between the blade and the glass.
I revisited the old corroded arm and refitted the new blade complete with the rubber that locks it into place. The Lucas motor was a lot happier moving the blade. I then proceeded to clean up the rust pitting and the grim of 60 years. Under each end of the arm is brass similar to the dash instruments that had a thin chrome type of plating. Some left over cutting compound from the paint and a hit with the buffer brought it up well. Doesn't look original as it is too shinny though it is the straight style of arm and sits better in the parked position.
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