Hello,
I have a broken plastic liner that is covering some sort of spring within the window. The plastic covering is extremely brittle and breaks off more and more each time the window is opened and closed. Is this covering something that I can buy a replacement for? There are no markings on the windows themselves unfortunately.
Broken part
Quick Learner from Chicago
Sep 4, 2025 8:27 pm
2 Replies
Tom from SWISCO
Sep 9, 2025 1:24 pm
This part is called a spiral balance. This appears to be an older tilt window style, but it's pretty standard. The modern replacement options for this will be either the 3/8" diameter Series 900 or the 9/16" diameter Series 600.
Your next step is to remove an old balance and then measure the diameter of the plastic tube to confirm which size is a closer match. The video below will also offer more insight on how these work.
Related Videos