I am replacing the broken sash cords in my home. It was built in 1927 and everything I have found says that there should be some sort of access panel to remove but try as I might, I can not find any such panel. There is a small slit, maybe an inch wide, that I can see the old weight and broken cord, but it isn't large enough to get the weight through. Is it possible that the panel has been covered in 80 years worth of paint that I should keep looking, or am I going to have to remove all of the window casings? Thanks for all your help!