Window putty

[DIY Lisa]

Hi, can anyone give me some advice?
I have a large-ish old metal framed window in one end of my garage and the putty is falling off and water and damp is getting in. Can I 'patch' putty it or do I need to take the whole window out and re-do the putty completely? Is this an easy DIY job?? I would be very worried about breaking the glass - there are three sections to the window.
Thanks

[welsh brickie]

its best if you remove the old putty first.Take an old wood chisel and a hammer and chip away the old stuff,if you keep to the front of the frame away from the glass you wont break it,and it comes away quite easily.
When you apply the new putty,spit into it,It will be a lot easier to apply,water dosent work, I know it sounds digusting but it works well.Then smooth off with the back of the chisel,spit on that aswell to stop it sticking.