The paint on my wooden window frames is peeling badly. Actually I only got the frames re-painted 3 years ago (undercoat and paint), but it is peeling again 'cos the wood is'nt in great shape. I don't really want to shell out for new windows at this stage. Is there anyway I can get some more mileage out of them? Any fillers/undercoats on and make them last for another few years?