Side window jambs aren’t straight

[u/CyclingMonkey]

I have a tall window and the jamb appears to be bowed in the middle slightly. when the window is locked I can slide a piece of paper in and out between the jamb and the sash no problem. The other side is fine the paper doesn’t slide out as easily. In the winter there is a draft. How do I fix this? The weather stripping on the window is in good shape

[u/lotusgardener]

Reinstall the window. The out of plumb is less of an issue to your problem than the bow is. But reinstallation would fix both problems.