How to Replace Window Handles for uPVC Windows: When to Replace the Gearbox

Replacing a window handle on uPVC windows is a common repair that can restore security and ease of operation. This guide explains when a gearbox (espag mechanism) should be replaced along with the handle, how to identify gearbox faults, and a clear step-by-step process for homeowners and tradespeople to replace handles and gearboxes safely and effectively.

Tools and materials required

• Cross-head and flat-head screwdrivers
• Hex key set (often 4 mm for espag handles)
• Replacement handle (see product suggestions below)
• Replacement gearbox/espagnolette mechanism (if required)
• Penetrating oil and multi-purpose lubricant (e.g. WD‑40 and silicone spray)
• Rag and small container for screws
• Tape measure or ruler
• Masking tape and marker for alignment marking
• Safety gloves and eye protection

Consider a handle such as the TSS Cockspur Window Handles for espagnolette windows, or the TSS Cockspur Window Handle for cockspur-style windows, and the TSS Offset UPVC Window Handles for a robust, general-purpose replacement. Choose a handle that matches the current fixing type (espag, cockspur, casement) and backset/spindle size.

When to replace the gearbox

The gearbox (espag mechanism) requires replacement when the handle operation remains poor after changing the handle, or when visible symptoms indicate internal failure. Typical signs include:

• Handle moves with little or no resistance but the window does not lock or unlock.
• Grinding, crunching or catching noises when operating the handle.
• The handle returns slowly or sticks halfway.
• Multiple locking points fail to engage despite correct handle movement.
• Metal fragments or excessive wear visible in the sash groove or on the mechanism.

A worn gearbox compromises security and can damage the lock keeps on the frame if left unattended.

Assessing the mechanism before removal

Before removing the handle, perform a quick assessment:

• Check handle fixings for loose screws and tighten. A loose handle sometimes mimics gearbox failure.
• Operate the handle with the window open and closed to determine whether the failure is independent of the sash position.
• Apply a small amount of penetrating oil to moving parts and test again. If operation improves, a full gearbox replacement may not be necessary but monitor for recurring problems.

If symptoms persist, proceed to remove the handle and inspect the gearbox.

How to remove a uPVC window handle (espag style)

1. Close the window and place masking tape across the handle and frame to mark the current alignment if required. 2. Locate and remove the handle grub screw or fixing screw; some handles hide these under a spindle cover — gently lever off the cover. 3. Slide the handle off the spindle. Keep screws and small parts in a container. 4. With the handle removed, operate the gearbox by turning the spindle (use the old handle or a hex key). Observe the rod or lock mechanism movement and look for broken or worn teeth and corrosion. 5. If the gearbox is serviceable, clean and lubricate. If not, mark and measure the gearbox configuration for replacement.

Replacing the gearbox (espagnolette)

1. Identify the gearbox type: espagnolette rods are either screw-in rods or hooked/clip-in types. Measure the distance between the top and bottom fixings if replacing the entire rod assembly. 2. Remove any faceplate screws and carefully withdraw the espag or gearbox from the sash. Smaller windows may require gentle manipulation to access the fixings. 3. Fit the new gearbox or espag rod, ensuring the correct orientation (top and bottom locking cams aligned). Secure the mechanism with the original fixings or the supplied screws. 4. Reattach the handle onto the spindle and tighten the grub screw; do not overtighten as this can strip the grub screw or damage the spindle. 5. Operate the handle slowly to check for smooth movement and engagement of all locking points. Adjust keeps on the frame if necessary to ensure locks engage crisply.

Replacing a cockspur handle

Cockspur handles mount on the face of the window sash with screws through the handle plate into the frame and operate a spur to pull the casement shut. 1. Unscrew the handle fixings and remove the old handle. 2. Clean the mating surfaces and fit the new TSS Cockspur Window Handle making sure the spur engages properly with the frame rebate. 3. Tighten screws evenly to avoid distorting the handle plate and test operation.

Common adjustments after replacement

• Realign keeps: Worn keeps may prevent the new mechanism from fully engaging; adjust keep position slightly to ensure positive locking.
• Replace worn keeps if alignment cannot be achieved.
• Apply silicone lubricant to moving parts, not heavy grease which attracts dirt.
• Check handles for correct backset and spindle square size; an incorrect spindle length can cause poor operation.

When to call a professional

Trade involvement is recommended if:

• The espag mechanism is integrated into a sealed unit or inaccessible sash.
• The window is large, heavy or the locking points are badly corroded.
• Repair requires replacement of welded corners or sash frame components.

A competent tradesperson can replace espagnolette rods, re‑profile keeps and guarantee alignment.

Final testing and maintenance

After replacement, perform several open/close cycles and lock/unlock cycles to ensure consistent engagement. Keep a simple maintenance schedule: lubricate annually, check handle fixings and keep alignment, and inspect for wear. A quality handle such as the TSS Offset UPVC Window Handles fitted correctly will offer reliable performance for years.

Reliable diagnosis and careful replacement prevent recurrent problems and protect the security and functionality of uPVC windows. For a deeper dive into handle types, fitting guides and troubleshooting, consult the comprehensive resource: Window Handles Guide

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