A set of metal door lock mechanisms, including cases and gearboxes, typically used in multipoint door locks.
Diagram showing gearbox measurement with labels for Backset (A) – distance from lock strip edge to center of keyhole, and PZ (B) – distance from center of keyhole to center of spindle.
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A set of metal door lock mechanisms, including cases and gearboxes, typically used in multipoint door locks.Diagram showing gearbox measurement with labels for Backset (A) – distance from lock strip edge to center of keyhole, and PZ (B) – distance from center of keyhole to center of spindle.

Fullex SL16 Gearbox – Replacement Centre Case for uPVC Multipoint Door Lock – 35mm/45mm/55mm Backset 68mm PZ

FullexSKU: HS3262
162 reviews from verified buyers
Price:
£49.99

Key benefits

  • Direct Fullex replacement - matches the model in your door
  • Restores multipoint lock function - saves replacing the full strip
  • Check the model on your existing case - before ordering they vary

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Description

Fullex SL16 Replacement Gearbox

The Fullex SL16 centre case gearbox is the mechanism inside your uPVC door that is operated by the handle. It is the part most likely to fail when a multipoint door lock stops working.

Replacing just the gearbox is far more cost effective than buying a complete new lock. The centre case re-attaches to your existing locking strip.

Key Measurements

The most important measurements are the Backset (35mm, 45mm or 55mm) and 68mm PZ.

This gearbox is non-handed, fitting both left and right-handed doors.

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Frequently Asked Questions

The Fullex SL16 gearbox is the core component of a multipoint locking system. It controls the handle and key operation, ensuring all locking points engage securely along the door.

Common signs include a stiff or loose handle, difficulty turning the key, or the door not locking properly. These issues often indicate internal wear and should be addressed early.

No, compatibility depends on measurements such as backset, PZ centres, and the specific lock design. Always match your existing gearbox specifications before purchasing.

Yes, in many cases the centre case gearbox can be replaced on its own, making it a cost-effective way to restore your door’s functionality.

Regular checks can help prevent sudden lock failure and avoid getting locked in or out. Learn more in Check This Before Your Next Let-In: Is the Door Gearbox Still Fit for Purpose.