Window screen sticking on 400

X2 on the dry silicone spray.  I bought it at Walmart I believe as RV window spray. 

@Michael49, I don't know if it will help, but here is a thread that discusses the window track fuzz, which is intended to keep out small insects, like mosquitos and no-see-ums.  Our 320 S front window has always been a little tight to move up and down, but it helps to open and close it with two hands, holding the shade framing about 1/4 way in from each side of the window.  Maybe try the silicone and try opening and closing it in this manner.  Also, look really close along the side tracks of the window frame to see if there is something (e.g., the string or fuzz) that is impeding the path of the shade.  Maybe there is something that just needs to be slightly adjusted or pushed aside.

https://tab-rv.vanillacommunity.com/discussion/6965/mosquito-fix-for-t-b-windows/p4

Mine did the same on day-1. Nucamp replaced on warranty. New one much better, but not perfect. Thanks for tip on lube!

I restrung my kitchen window also and here is what I used: https://www.amazon.com/gp/product/B01LFJ2JYO/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

There are several sizes and this seemed to work.  It looks about like the size that was previously used.

As far as moving the shades I agree with the recommendation to use two hands.  That does make it smoother and I also find it works better if I just move the screen and shade separately rather than hooked together, for what it's worth.

@TNOutback - it does sound like something is binding and could be an issue with the string.  I would recommend removing the entire screen and doing a good visual inspection.  There are four screws - one in each corner - and removing is very easy.  Just pop the little corner covers off and remove the screws.  Be careful not to drop any down the heat transfer slot under the window!  On mine the screws were #2 square drive I believe.

I could see on mine that the string wasn't riding on the end of the aluminum piece correctly where the string transitions from horizontal to vertical and was shredding.  It was also binding.  And if I didn't get it just right I still have about a mile of string to redo it again!

Fixed.  It ended up being something very simple, but I couldn’t understand how the screen mechanism worked until I took it apart.  The center-left string was in bind and prevented the aluminum bar from being pulled down.  After disassembly, I realized the center-left string actually feeds to the right side of the window, and the black string was in a pinch-bind on the right end of the aluminum bar.  Once I released that pinch, the screen would pull down just fine.

@Michael49,
You might want to check if there is any debris or dirt in the screen track, as that can make it stick. A quick clean and a bit of silicone spray on the tracks can help the screen slide more smoothly.

@Cherokee Slight correction, Boeshield T-9, excellent product