When a uPVC window won't close or lock, the cause is nearly always one of four things: the sash has dropped on its hinges, a locking keep has moved, the handle's gearbox has failed, or a hinge is worn or bent. Most of these are repairable parts rather than a reason for a new window. The key rule is not to force the handle — that turns a simple adjustment into a broken gearbox.
This guide helps you work out which fault you have and what to do about it.
Work out what's happening
- Sash rubs the frame at the bottom corner — dropped sash or worn hinge
- Window closes but handle won't lift to lock — locking points miss their keeps
- Handle turns freely but nothing moves — broken gearbox or spindle
- Handle won't move at all — seized gearbox or locked handle
- Window won't stay shut in wind or opens by itself — worn friction hinge
Dropped sashes and worn hinges
Friction hinges at the top and bottom of casement sashes carry the weight. As they wear, the sash drops and catches the frame. Some can be adjusted; badly worn or bent hinges are swapped for new ones of the right size. Restrictor hinges can be fitted at the same time on upstairs windows.
Keeps and locking points
Multi-point locks use rollers or hooks that engage keeps on the frame. If a keep has worked loose or the sash has shifted, the rollers miss. Tightening or repositioning keeps is a small job, but getting the compression right so the window seals is the part that takes experience.
Handles and gearboxes
The handle drives a gearbox inside the sash that moves the locking bar. A snapped spindle or failed gearbox means the handle spins or jams. Replacement gearboxes need to match the backset and type in your window, so it helps to have someone identify the right part.
Safe checks and when to call
You can check for loose screws on hinges and keeps, clear debris from the frame and put a drop of light oil on the locking points. If the window is stuck open, can't be secured, or the handle is broken, call for help — an insecure ground-floor window shouldn't be left. And if the frame itself is warped or cracked, that is when replacement is worth talking about.
Common questions
Tightening loose screws and oiling locks is fine. Hinge and keep adjustment is best done by someone experienced so the window still seals.
The locking points are usually missing their keeps because the sash has dropped or a keep has moved. Don't force it.
Rarely. Hinges, keeps and gearboxes are replaceable parts.
Call 07538 882579 or use the contact form to arrange a visit.
Want a straight answer on your own windows or doors?
DM Installations fits and repairs windows and doors across Central Scotland — Cumbernauld, Glasgow, Falkirk, Stirling and the surrounding towns. Free survey, written quote, and an honest answer on whether you need a repair or a replacement.
Related guides
How to Fix a Draughty Window
Track down where the cold air is really coming from and fix it for under £30 in most cases.
How-toHow to Adjust a uPVC Door
Which screw does what on flag, butt and rebate hinges, and how to get a dropped or sticking door closing properly again.
When to call a proSigns You Need New Windows
A proper inspection checklist so you can tell a repair job from a replacement job before anyone quotes you.