How to Fix a Broken Window Balancer: Step-by-Step Guide

A double-hung window that will not stay open, or one that feels heavy and fights you on the way up, almost always has a failed window balance. The balance system — whether a spiral spring, block-and-tackle pulley, or coil spring — counterweights the sash so it slides smoothly and holds any position. Replacement is straightforward once you identify the balance type.

What You Need

• Spiral window balance replacement kit ($8–$15 each — order based on your balance’s length and tension code)
• Block-and-tackle window balance replacement ($12–$25 each if your window uses pulley balances)
• Window balance installation tool / tension tool ($8–$15 — makes tensioning spiral balances much easier)
• Flathead and Phillips screwdrivers
• Putty knife (for removing window stops on older windows)
• Measuring tape
• Pencil for labeling removed parts

Step 1: Identify Your Window Balance Type

Before ordering parts, you need to know what type of balance system your window uses.

Spiral balance: Look for a cylindrical metal tube approximately 3/4 inch in diameter running inside the window jamb channels on each side of the sash. A metal rod with a coiled spring inside the tube attaches to a pivot shoe at the bottom and connects to the sash at the top. This is the most common type in windows manufactured after 1990.

Block-and-tackle balance: A wider, rectangular channel on each side of the jamb contains a small pulley system with a cord that attaches to the sash. Common in vinyl replacement windows from major manufacturers like Andersen, Pella, and Simonton.

Coil spring balance: A flat wound spring in a metal housing, found in older wood and aluminum windows from the 1960s to 1980s.

Sash weight: A heavy cast iron weight hanging on a rope inside the wall cavity, accessed through a small access panel in the jamb. Found in pre-1960 wood-frame windows.

This guide focuses on spiral and block-and-tackle balances, which cover the vast majority of windows in homes built after 1970.

Step 2: Order the Correct Replacement Balance

For spiral balances: Tilt the sash in (described in Step 3) and unhook one of the existing balances. Look for a sticker or stamp on the tube that shows a two-character code — typically a letter (tube length) and a number (spring tension). Common codes include “S380,” “S290,” and similar. Order a replacement with the same code. If there is no code, measure the tube length in inches and weigh the sash — the tension code is matched to sash weight using a chart available from suppliers like Swisco.

For block-and-tackle balances: Measure the length of the balance channel and note your window brand and series. Order accordingly from a window parts supplier.

Step 3: Tilt In and Remove the Sash

On most modern double-hung windows with tilt-in sashes:

1. Raise the lower sash approximately 6 to 8 inches.
2. Locate the tilt latches on each side of the sash — small plastic tabs at the top corners of the sash. Press both latches inward simultaneously.
3. While holding the latches pressed, tilt the top of the sash toward you into the room. The sash will pivot on its pivot pins at the bottom.
4. Support the sash with one hand and disconnect it from the balance shoes by lifting the pivot pins out of the shoe slots.
5. Set the sash aside on a padded surface — a blanket on the floor works well.

For older windows without tilt-in function, the window stops (thin strips of wood or vinyl) must be removed first using a putty knife to pry them off the jamb. Then lift the sash straight up and out.

Step 4: Remove the Old Balances

Spiral balances: The balance attaches to a pivot shoe at the bottom of the jamb channel, and the top of the tube is held by a bracket or clip at the top of the channel. Unhook the coiled rod tip from the pivot shoe, then slide the tube out of the channel by releasing the top bracket.

Block-and-tackle balances: The balance cord or strap has a connector that attaches to a shoe or clip on the sash or jamb. Release the connector, then unscrew the balance housing from the jamb channel.

Note the orientation and installation of the old balance before removing it — a photo is helpful.

Step 5: Install the New Balances

Spiral balance installation:

1. Insert the new spiral balance tube into the channel from the top, tube end first.
2. Secure the top bracket or clip.
3. Use the balance winding tool (or a flathead screwdriver) to turn the coiled rod at the bottom of the tube, tensioning the spring. The number of turns required depends on the sash weight — typically 3 to 6 turns for a standard sash. Consult the replacement balance documentation for the correct turn count.
4. Hook the coiled rod tip into the pivot shoe at the bottom of the channel.

Block-and-tackle balance installation:

1. Screw the balance housing into the jamb channel using the existing mounting holes.
2. Route the cord or strap as indicated in the balance instructions.
3. Attach the connector to the sash clip.

Step 6: Reinstall the Sash and Test

Align the sash pivot pins with the pivot shoes in the jamb channel. Press the sash flat back into the jamb — the tilt latches will snap back into place automatically on most modern windows.

Test the sash by raising and lowering it through its full range. It should move smoothly with light pressure and hold any position when released. If the sash still falls or feels too heavy, the spring tension may need adjustment — add one more turn on spiral balances and retest.

When to Replace the Whole Window

If the window frame is rotted, warped, or the sash itself is damaged, balance replacement alone will not fix the operating problem. In that case, consult a window contractor about full sash replacement or window replacement.

Related Reading

• How to Weatherstrip a Double-Hung Window
• How to Fix a Stuck Window
• Window Replacement Cost: What to Expect