window parts

Hi Stella. Let me see if I can help you wrap this up. Let's go through each part one at a time.

• Spiral Balance--If the diameter of the spiral balance's outer tube is 3/8", and if the tube not including the tip is 27", then it definitely sounds like you have a S900-27. You will need to select a color tip option. These color tips reflect the amount of weight the balance is meant to support. If you're uncertain what color tip you have--which happens a lot with older balances--weigh your window sash. You can then match that exact weight with the corresponding color option: If the sash weighs 10 through 22 lbs, go with the red tip. If it weighs 24 through 34 lbs, go with the yellow tip. If the balance has a larger diameter, let us know first. 

• Pivot Shoe--This is either a 15-188 or 15-178. The only difference between these two pivot shoes is the thickness. The 15-188 is 1/2" thick, the 15-178 is 17/32" thick. If you think your old shoe is a bit thicker than 1/2", chances are this this is an older version of the 15-178. But do your best to check just to be safe. 

• Pivot Bar--This is the pin that connects the sash to the pivot shoe. See our 26-226. The most relevant dimensions, other than the shape of the end that inserts into your pivot shoe, is the distance between the end of the pin that fits into the shoe and the center of the mounting holes. As long as one of these holes aligns with your old pivot bar, this can work for you. 

Let me know if you have any other questions.