The windows, themselves, are nice and I can understand trying to
preserve them. It would help greatly to have photos of the outside of
the window to understand the problem completely...hope the frames aren't
level with soil, and that soil slopes away from foundation.

Taking the windows apart, stripping, priming and repainting is good
first step, but not entire solution. It helps, when repainting, to be
sure that the coat of paint bridges the gap between the frame and the
pane....keeps rain and condensation out of the wood so paint doesn't
peel. Assuming the exterior sill is sloped, a simple sheet of
plexiglass on the outside, screwed to the frame, might help the windows
weather and provide better insulation.