We had new windows put in five years ago. They are impact windows. Two windows on one side of my house that gets a lot of sun have some damage to the caulk. The rest of the windows are doing great. Last thing I need is water coming in with a bad storm. I'm planning on doing this myself. What kind of caulk would you recommend and should I tear out as much of the old caulk as possible before filling the gaps? As always, I appreciate the help.