Peachtree G1888 Type A balances
I'm afraid I cannot identify what you have based on this information alone. The stamp only indicates the spring strength calibration and is not otherwise used to identify your balance. I recommend that you look at our Channel Balance Home Page and follow the steps in order to find the Series that best matches what you have.
If you can't find a match here, please show us a picture of the top nylon attachment and a picture of the bottom nylon attachment and we will do our best to find a replacement.
The problem you're having is most likely that the balances in your window are no longer working properly. We would need to see a picture of your balance to recommend a replacement. Here is a video that will walk you through removing the balances. Thank you!