Replacing the cord on a sash window- diy nightmare

When you open a sash window ropes attached by a cord to weights help to open it by balancing the weight of the window. Once these cords have broken it is really difficult to open the window because it is so heavy.

I watched a couple of videos on the internet. I read a page. I went to a course on how to do this about a year ago.
Very glib sentences are used- check the pulley is moving, if not oil it. Haha- We ended up removing it from the window and scraping off 100 years (literally) worth of paint.

Remove the pocket (a piece of wood in the side of the window that allows access to the weights). Haha again - this took about 40 minutes. However the window now moves so there was a sense of satisfaction in the end. The whole job took hours. I suppose it could have been worse.