Part Number 28300 channel balance

Thanks for writing in your question. The number you have provided just tells us the spring calibration inside the balance. In no way does it help with the identification of the part. In order for us to make a determination on a replacement, we will need to see photos showing the balance removed from the window. We will also need for you to provide us with the metal length measurement of the balance. Once we have all the photos and information we need, we can get started on searching for a match. 

Thank you for getting back to me with your photos. Looking at the nylon fittings of your balance, it looks more like our S351-29 and S390-29. The difference between these two balances lies within the 'depth' measurement of the bottom balance shoe. Measure the depth of your bottom shoe, just as it is shown in the diagram below, to determine which of the two balances is the better match. Whichever one chosen will go with a 2830 option that supports a sash weight of 16-23 pounds. 

Comparison of 15-001 & 15-002

Yes, that is correct.