Replacement for 30 3 KN Caldwell balance is needed

Hi there Dmitry.

I'm afraid we can't suggest a replacement based on this information alone. The stamp on the metal channel isn't a part number so we'll need more information. Can you remove an undamaged balance from the window? We'd like to see a few close-up shots of the top and bottom fittings. 

Thank you! I'm certain we can help with this. Before I make a recommendation, can show us a photo of the inside of the metal channel where the innerspring connects to the pulley mechanism? That'd be located in the middle of the channel. I apologize for not asking that before! 

Perfect! The S350-31 with the 3030 stamp option is my recommendation based on the photos you've uploaded. Take a look at the specifications for this part and let me know if you have any questions. 

I'm afraid I can't ID the top sash guide without a photo. We'd have to see photos of one in undamaged condition removed from the sash. Angles of the front and the side are especially helpful. 

Thank you! The 18-009 resembles what you have here. Review the specifications and see how they compare with yours.

Side view of 18-009

Detail of 18-009