It’s hard to say because the windows are filthy both inside and out and I can really only see once both surfaces are clean. I do feel though that the scratches are being created by the blade edges. Suffice to say, I like your sandpaper idea and i know exactly what you’re saying. I’ll be trying this on my next job.
Before we close this topic off, do you have a ballpark time frame that you use to replace blades?
Thank you for devoting your time to help a fellow community member out. Greatly appreciated.