My garage window has very dry old putty holding the glass in and some of it has started to fall out. Can I remove the old putty and put new in? the window does not let water in so I would like to avoid replacing the whole thing. If I can chip out( not really a case of chip out as most is ready to fall out ) the old putty and replace it with new, do I have to paint over it? and if so do I have to let the putty dry for a particlar length of time? I would be grateful of any advise as I am new to DIY. :?