[Dr. Dyno]

There was one experience where the blades were being changed and the person did not lower the blade but allowed it to snap back onto the windshield. The windshield cracked and had to be replaced.

I just changed the blades on our new-to-us 2011 yesterday. And yes, with the blade removed there is danger of the bare metal end the arm snapping down and cracking the windshield. To avoid that I set the end gently against the glass while getting the new blade ready and never let go of it until the new blade was on.

I have often raised the blades off the windshield to prevent them freezing against the glass. Even if one of them somehow snapped back down, with the force spread across the whole blade it likely wouldn't cause damage.

 

[Dr. Dyno]

I'm not as worried about spring stretch as damage to the wiper motor if it tries to run against frozen wipers.