The plastic guides installed at the ends of a block and tackle balance help position the balance inside the jamb and connect it to the window’s sash-support system. Selecting the correct guides requires identifying the top and bottom ends, determining whether each guide is winged, and measuring the bottom-guide depth.

Before You Start

Tools and information you may need:

• Original block and tackle balance
• Original top and bottom guides
• Tape measure, ruler, or digital caliper
• Phone or camera for reference photos
• Paper or notes app for recording measurements
• Any visible balance stamps or manufacturer markings
• Photos showing how the balance was installed in the jamb

Important: Do not select a replacement guide by color alone. Age, sunlight, dirt, and manufacturing differences can cause otherwise compatible guides to appear different.

Keep the original balance and guides until the replacement assembly has been installed and tested.

A block and tackle balance contains a spring, cord, pulley system, and metal channel. Plastic guides are installed at the ends of the channel to help the balance fit and operate correctly inside the jamb.

• Top guide: Located at the spring end of the metal channel.
• Bottom guide: Located at the pulley-and-clip end of the balance.

The two guides are not interchangeable. Their shapes and functions are different, even when they are made from similar plastic.

Identification shortcut: Spring end equals top guide. Pulley-and-clip end equals bottom guide.

A winged top guide has small horizontal tabs extending from the sides of its body. A non-winged guide has a narrower profile without those side tabs.

Compare the following:

• Presence or absence of side wings
• Overall guide width
• Shape of the upper prongs
• Opening through the guide body
• How the guide fits over the balance channel
• Any molded tabs, ribs, or retaining features

In the image, the guide on the left is winged and the guide on the right is non-winged.

The side wings help position and stabilize the balance inside the jamb channel. They may reduce side-to-side movement and help maintain the intended relationship between the balance, frame, and sash.

A window originally designed for winged guides may provide more jamb clearance than a system using narrow non-winged guides.

Do not remove the wings or substitute a winged guide for a non-winged one unless the replacement has been confirmed for the specific window system.

Inspect the sides of the bottom guide for projecting tabs similar to those found on the top guide.

A winged bottom guide:

• Has horizontal projections extending from the sides
• Occupies more width inside the jamb
• May help center or stabilize the lower end of the balance

A non-winged bottom guide:

• Has no projecting side tabs
• Uses a narrower body profile
• May fit a tighter jamb channel

In the image, the guide on the left is winged and the guide on the right is non-winged.

Bottom guides are available in several depths. Measure the projecting plastic body from the back of the metal channel to the farthest front edge of the guide.

1. Lay the balance on its side on a flat surface.
2. Position the end of the ruler at the back edge of the metal channel.
3. Measure to the farthest projecting point of the bottom guide.
4. Keep the ruler parallel with the balance channel.
5. Record the measurement without rounding aggressively.

The non-winged guide shown measures slightly less than 1-1/8 inches deep.

A size identified as common may still be incorrect for your balance. Always measure the original guide.

A loose guide can be measured separately, but first determine how much of the guide normally overlaps or inserts into the metal channel.

Record:

• Total guide length
• Installed projection beyond the channel
• Guide width without wings
• Total width across the wings
• Body thickness
• Prong length and spacing
• Slots, openings, hooks, and retaining tabs

When the original is broken, save every piece. Reassembling the pieces beside a ruler may reveal the original dimensions and profile.

A matching guide from the balance on the opposite side of the window can also provide a useful reference.

The guides must fit the balance’s metal channel. Before selecting guides or a complete replacement balance, measure the depth and length of the channel.

Record:

• Metal-channel depth
• Metal-channel width
• Length of the metal channel only
• Balance stamp or weight code
• Whether the channel is standard or extended
• Location of rivets, pulleys, and spring components

Do not include the plastic top or bottom guides when measuring the metal-channel length.

The stamp on the metal channel generally relates to the length and weight capacity of the balance. It does not normally identify the guide configuration by itself.

Record the complete stamp exactly as it appears, including dashes, spaces, letters, and suffixes.

Also photograph:

• The stamp close-up
• The entire metal channel
• Both guide ends
• The pulley and attachment clip
• Any manufacturer logos or patent numbers

Wing style and bottom-guide depth are the primary selection points, but the replacement should also be compared with the complete original profile.

Compare:

• Guide-body length, width, and thickness
• Overall width across any wings
• Number and shape of projecting prongs
• Slots and openings through the guide
• Rounded, square, or angled front profile
• Channel-engagement tabs or retaining features
• Guide orientation on the balance
• Clearance around the pulley, spring, cord, and clip

Replacing only the guide may be appropriate when the plastic component is damaged but the balance spring, cord, pulleys, channel, and attachment hardware remain in good condition.

Consider replacing the complete balance when:

• The cord is frayed or broken
• The pulley is cracked, seized, or displaced
• The spring is damaged or heavily corroded
• The metal channel is bent or distorted
• The balance no longer supports the sash
• Multiple guide components are broken
• The replacement guide cannot be secured reliably

Block and tackle balances are under spring tension. Do not disassemble the internal spring-and-pulley system unless the component is specifically designed to be serviced and the proper procedure is known.

Clear photographs help distinguish between guides that share similar measurements.

Include photos of:

• The complete balance from the open-channel side
• The complete balance from the back
• The top guide from the front, side, and end
• The bottom guide from the front, side, and end
• The bottom-guide depth beside a ruler
• The metal-channel depth and length
• The complete balance stamp
• The pulley, cord, and attachment clip
• The jamb where the balance was installed
• The sash attachment point or sash cam

• Confusing the top guide with the bottom guide
• Ordering by color alone
• Failing to check for side wings
• Measuring the bottom guide from the wrong reference point
• Rounding the bottom-guide depth too aggressively
• Assuming the most common guide must be correct
• Ignoring the balance channel size
• Using only the balance stamp for identification
• Comparing only the front of the guide
• Ignoring prongs, slots, tabs, and side-profile differences
• Discarding broken guide pieces before identification
• Replacing a guide on an otherwise damaged balance
• Discarding the original balance before testing the replacement

Before ordering, confirm all of the following:

• The spring-end top guide has been identified.
• The pulley-and-clip-end bottom guide has been identified.
• The top guide is correctly classified as winged or non-winged.
• The bottom guide is correctly classified as winged or non-winged.
• The bottom-guide depth has been measured.
• The full guide profiles match.
• The metal-channel depth and length have been recorded.
• The complete balance stamp has been documented.
• The replacement is compatible with the original balance series.
• The balance’s cord, pulleys, spring, and channel remain serviceable.

The top guide is located at the spring end of a block and tackle balance, while the bottom guide is located at the pulley-and-clip end.

Determine whether both guides are winged or non-winged, measure the bottom-guide depth, and compare the complete guide profile before selecting a replacement.

Also confirm the balance channel size, length, stamp, and overall condition so the guide and balance system remain compatible.