Thanks for providing images. Unfortunately we need to see a couple more views of each attachment. Identifying the plastic attachments at each end is what determines which replacement balance series you will need to order.
The stamp looks good. The first two digits represent the spring measurement (if you add 1" you will get the channel length - in your case 25"). The second two digits represent the spring strength.
By the way, 'coil balances' are a different type of balance from what you have. You have what is commonly referred to as either a channel balance or a block and tackle balance.
i tried to give enough views of each plastic detail on each end .....hope this helps