Step-by-step fix
Step 1: Confirm the sash lock and keeper are the real problem
- Close and lock the window the way you normally would.
- Look for obvious hardware failure such as a broken latch, bent keeper, missing screws, stripped screw holes, or a lock that turns but does not pull the sash tight.
- Unlock and relock the sash while watching whether the cam on the lock actually catches the keeper.
- Check that the window sashes meet evenly. If they are badly out of line, the lock may not be the root cause.
- If possible, compare the problem window to another matching window that locks correctly.
If it works: You have confirmed the lock or keeper is damaged, loose, worn, or no longer catching correctly.
If it doesn’t: If the hardware looks intact but the sash is racked, swollen, or hard to close, fix the alignment or sticking problem first before replacing the lock.
Stop if:- The sash frame is cracked, rotted, or pulling apart around the lock area.
- The glass is loose or the sash feels unstable when you try to close it.
- The window will not align well enough for any lock to engage.
Step 2: Match the replacement and prep the window
- Open the lock and support the sash in a comfortable working position.
- Take a photo of the old lock and keeper before removing anything.
- Measure the old lock and keeper, including screw hole spacing and the height relationship between the lock and keeper.
- Make sure the replacement has the same handing and latch style so it will pull the sash together instead of missing the keeper.
- Score any paint around the hardware with a utility edge if needed so the old parts come off cleanly.
If it works: You have a replacement that matches the old hardware closely enough to install in the same location or with only minor hole adjustment.
If it doesn’t: If the new part does not match the old hole spacing or latch shape closely, return it and get a closer match before drilling extra holes.
Stop if:- The replacement hardware is clearly the wrong size or style for the window.
Step 3: Remove the old lock and keeper
- Back out the screws from the sash lock first and set them aside if they are still usable.
- Remove the keeper from the opposite sash.
- If paint or debris is holding the hardware in place, work it loose gently with a flat screwdriver or putty knife instead of prying hard on the wood or vinyl.
- Clean the mounting surfaces so the new hardware can sit flat.
- Inspect the old screw holes for stripping, cracking, or soft wood.
If it works: The old hardware is off and the mounting areas are clean and ready for the new parts.
If it doesn’t: If a screw spins without backing out, pull outward gently on the hardware while turning the screw to help the threads catch and release.
Stop if:- The screw holes are badly blown out, the sash material is crumbling, or the mounting area is too damaged to hold new screws safely.
Step 4: Repair weak holes and position the new keeper
- If old screw holes are stripped, fill them with wood filler or another suitable repair material and let it firm up enough to hold a pilot hole.
- Set the new keeper in the original location or align it to the old witness marks left by the previous hardware.
- Mark the screw holes with a pencil.
- Drill small pilot holes if needed, especially in wood, to reduce splitting and help the screws start straight.
- Fasten the keeper snugly without overtightening.
If it works: The keeper is mounted flat, solid, and in the correct position for the lock to catch it.
If it doesn’t: If the keeper rocks or will not sit flat, remove it and clean away paint buildup or debris under it before trying again.
Stop if:- The sash material starts cracking or the screws will not tighten because the mounting area has failed.
Step 5: Install the new sash lock and align it to the keeper
- Place the new sash lock on the meeting rail where the old one sat.
- Start the screws loosely so you can make small alignment adjustments before fully tightening.
- Close the window and test the lock engagement by turning it slowly toward the keeper.
- Shift the lock slightly as needed so the cam catches the keeper and pulls the sash together evenly.
- Tighten the screws once the lock engages smoothly without forcing.
If it works: The lock catches the keeper cleanly and pulls the two sashes together with a snug, even fit.
If it doesn’t: If the lock barely misses the keeper, loosen one piece at a time and make small alignment changes rather than forcing the latch.
Stop if:- You have to force the lock hard to make it catch, which usually means the sash is misaligned or the hardware is the wrong match.
Step 6: Test the repair in real use
- Open and close the window several times, then lock and unlock it each time.
- Check from inside that the meeting rails pull together tightly and the sash does not drift apart after locking.
- Look from outside if possible, or inspect the gap line, to make sure the sash closes evenly across the lock side and the opposite side.
- After a few cycles, retighten the screws if anything settled during the first test.
If it works: The window closes fully, locks without strain, and stays pulled together during normal use.
If it doesn’t: If the window still will not stay shut or the lock keeps slipping, recheck sash alignment and confirm the replacement hardware matches the original dimensions and latch style.
Stop if:- The sash still drops, separates, or shifts after the new hardware is installed, which points to a balance, alignment, or frame problem rather than the lock alone.
Replacement Parts
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FAQ
Do I need to replace both the lock and the keeper together?
Usually yes. They wear together, and a new lock may not catch an old keeper correctly. Replacing both gives you the best chance of proper alignment and a tight latch.
Why won't the new sash lock line up with the old holes?
Even similar-looking hardware can have different screw spacing or a different cam shape. Match the old part by measurements and latch style, not just by appearance.
Can a sash lock keep a window from sliding down by itself?
It can help hold the sashes together, but it is not a fix for a failed balance or a badly misaligned sash. If the window still drops after the lock is replaced, another part is likely causing the problem.
What if the screw holes are stripped?
Fill the damaged holes, let the repair set up, then drill small pilot holes and reinstall the screws. If the sash material is badly damaged or rotten, the area may need a larger repair before new hardware will hold.
Should the lock be hard to turn?
No. It should feel firm but not forced. If it takes a lot of pressure, the keeper is misaligned, the sash is not closing fully, or the replacement hardware is not the right match.