I have wooden window frames which are lots of small square panes of glass. The exterior has not been maintained very well, but i think the wood is still ok. When it rains heavily against the windows water gets in round the edges of some of the panes. How can i repair them? my intention is to sand the wood down and repaint the frames but i'm wondering if they need re-puttying or if i should use an exterior frame sealant instead and that would be enough?