I used to be an AUTO GLASS technician for about 30 years.
I just want to mention something we used in the shop to really clean the outside of the windshield: Cerium Oxide powder.
Pink fine powder. You can buy it off Amazon or try asking your local auto glass shop if they sell to the public.
You just need a pinch of it, toss onto a wet windshield. Use a gloved hand (nitrile -latex / mechanic's gloves) , make a paste and do circular motions all over the surface of the glass.
When done, use a garden hose and wash off the windshield/wash off your car's paint. KEEP YOUR DOG/CAT inside so it does not go lap up the waste water on the ground and also hose off your driveway/shop floor.
Anyways, i'm sure there are YouTube vids explaining how to use Cerium Oxide on your windshield. This Cerium Oxide really cleans all the crud off the glass, the road film, oils and waxes. Stuff that can make windshield wipers chatter . Once clean, the wipers will glide effortlessly across the glass.
Also, if you have fine wiper burn marks (nothing too deep) or fine scratches, you can use a good power drill with a buffer attachment , make the Cerium oxide paste and try buffing the scratches out. That can be more involved, but worth it.
* regarding the wiper issue inkuisitive is having, I agree with others here, could be incorrectly installed windshield wipers/ could be a worn down wiper motor and time to replace it. Also, if you are handy, maybe the wiper motor might benefit from being sprayed with electronic contact cleaner. Might even have to remove it, open it up and spray inside it. Not saying for sure this will work, could be dirty/corroded parts inside and maybe it just needs a good cleaning. A can of electronic spray cleaner is cheap versus buying a new wiper motor plus the labor .
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