These are the rags so far from cleaning.

Try your vacuum with a brush attachment.

+1. With that old a unit, removing anything can be tricky and possibly disastrous. I would try to vacuum them in place...carefully...first.

I don't see screens....do you mean with mesh screens?

Do you open those windows? If not, it probably makes more sense to have storm windows rather than screens, if these windows are in conditioned space. I had windows like that in the attic of my previous house with screen held in with two hooks on the removable portion and loops in the window frame. Mine were quite a tight fit and we only removed them once when we painted the windows and trim work. It was much easier to paint from inside.

If I remember correctly, we washed them with soap and water and an old toothbrush but mine were actually brass screening and not fragile at all.