(03/12) unique 30-C-30

Hello, Edwina. Your sash lift looks like our 26-116 and your balance could either be our S390-31 or S351-31, depending on the depth of your bottom shoe. You'll have to measure your old shoe and look over our dimensions to confirm the better option.

Great, thank you! Let me know whenever you can.

I'm sorry, I'm a little confused. I had narrowed your balance selection down to either our S390-31 or S351-31. The only difference between these balances is the size of the bottom shoe, which we cannot make out from just photos. I'm afraid that the size of the window frame doesn't really tell us anything in regards to whether the S390-31 or S351-31 will work for you.

I recommend looking at the store page for both balances and looking over our dimensions and information. That will allow you to determine which balance will work for you between the two that I recommended.

The stamps are not used for identification. All they do is indicate the strength rating of the spring. In your case, the 24-C-30 would be a 25" long channel balance with our 2430 stamp option. This carries 15 through 19 pounds. Meanwhile, the 30-C-30 would be a 31" long balance with our 3030 option. This carries 16 through 23 pounds. That's all I can tell you based on the stamps.

As for your new photos, it's hard to tell from just a tape measure held up to the part. It looks like it's more than 1", which makes me think our Series 390 is what you want. You'll have to use your best judgement, though. I cannot tell you with 100% certainty that this is what you have.

If you install the smaller Series 351, the worst thing that will happen is that your sash may wiggle a bit when you operate it. If you wanted to play it safe, I actually recommend going with the larger Series 390. If it's the same size, then great! If it's too big, though, you can always shave it down a hair until it's the size you need.

The top and bottom nylon attachments come pre-attached. All our balances are fully assembled and ready to install out of the box.

If the Series 390 is too big, you'll notice soon enough. Because the shoe is bigger, it will be very tight in the jamb track, which will make your window very difficult to open and close due to friction. You don't want to keep it in there for long.

Each window needs two balances, yes. I recommend watching the video below to understand how they are meant to be installed.