Before you can replacing broken or damaged sash ropes, or or renovate your sash windows completely, you need to remove the sashes from the frame.
Remove the fixing bead round the inside edge of the window frame carefully. Start in the middle of a long bead by gently prising it away from the main frame by around 2.5cm with an old chisel. Now tap the bead sharply back into place. The pins securing it should come up through the surface of the wood; remove them with pliers. If this is not effective, you can drive a wedge in the middle and use a chisel to lever progressively towards the ends of the bead.
The lower inner sash can be taken out and rested on the window sill. Before removing it, mark in pencil on the front of the sash the place where the ends of the sash cords come, and make a corresponding mark on the frame. Remove the nails with a pair of pincers, while holding the sash cords. If the rope is unbroken, this prevents the weights at the other end from falling behind the stile boards.
Next, remove the parting bead between the sashes, using the chisel to ease it out of its groove.
The upper, outer sash can be removed next and stood aside. Repeat the marking procedure.
Finally, unscrew or lever out the pocket covers. Take out the weights by pulling them through the pocket openings.