How old are your Andersen windows and what is wrong with them?

Sorry I have no idea what your pictures are trying to illustrate. Have you looked at sash packs? They can be a good option if your jambs are in good condition.

I would reglaze the wood windows, if they are otherwise in good condition, and just need some reglazing, and not replace them. Those windows should last for many years yet. My wood windows are Anderson, and were put in this house when it was built in 1966. They are still in decent condition. Mine are not double paned. I have storm windows, and I replaced all the storms, over the last two years with nice white Larson ones. Just in time, I guess, because, I think I read that Larson isnt making them anymore.

My Andersen windows are ~30 years old, 4 or 5 of them on the first floor are rotting on lower part of the sash (see picture below). The rest are ok except a couple of the windows you could feel the draft, and one window we saw water blowing in between the bottom sash and sill once when it was raining heavily.

Picture of my window rotting sash, raining right now when I'm taking this picture:

Thanks HALLETT & Co. for suggesting the sash packs option, I will look into that. My jambs appear to be in good condition, except some windows had wood rot at the open wood sill ends where I applied wood hardener ~5 years ago and it helped to stabilize I think (see lower right corner of the picture above).

The two pictures of my friend's windows I was wondering if the gap around the corner between the new frame and the old one and the exterior caulk were supposed to look like that for inserts replacement, or was it just bad installation? With inserts installation, do you still have to re-caulk between the exterior new and old frames every several years? Thanks.

I would definitely recommend new Andersen sash over vinyl replacement inserts. Very easy to install.

Found the Andersen Narroline 200 windows lower sash on parts.andersenwindows website, $430 I'm planning to order one first to try to install it myself. Really surprised to see the exterior frame/sash of these Andersen windows not covered with any rigid vinyl or any protection. Guess I should have painted the exterior frame/sash when we moved in the house several years ago. Thanks everyone.

The frame would have been vinyl clad and the sash prefinished painted white, unless they go back to the 1960's or early 70's, then they would have come only primed as tha was before they were using the vinyl and the polyurea painted finish.

Thanks millworkman the house was built in 1990's. Yes exterior frame covered in vinyl except the sill ends are not wrapped. My bad...I meant to say that I should have re-painted the exterior sash when we moved in the house. Not sure if the previous owner had done it or not, but I saw a couple of neighbors re-painting theirs recently.