Window Mechanism Broken? Here’s What To Do

If your window suddenly won’t open, you’re likely frustrated. Whether it’s because you’re boiling alive in a home that now can’t air out, or you just like fresh air, it’s never nice. Luckily, those of us at DreamyHome have been exactly there, and know what to do. Replacing a window mechanism that’s broken can seem hard, but it’s actually a rather simple process.

To replace a window mechanism that’s broken, you’ll need to remove the mechanism and trim. After that, it’s a straightforward process.

Let’s get right into it – no sense in making you wait any longer, right?

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Window Mechanism Broken: Replacing It

Okay, you won’t need much to do this, surprisingly. You’ll want a screwdriver and utility knife, and obviously a new casement window crank. Now, let’s just hop right into the fix.

Replacing It, Part 1

To fix a broken window mechanism:

  1. Inspect your window mechanism. Depending on what’s broken, you may need to replace only a part or the whole thing. If the spline, gears, or crank arms are damaged or missing, you’ll need to replace the whole thing.
  2. Using pliers to grip the mechanism (assuming it’s snapped off) open your window. This may take a bit of force, but it needs to happen. Be careful not to damage your window. Open it until the crank arm guide bushing aligns with the notch in the guide track on the window. Push down on the arm, removing it from the window, and then push the window out until it fully separates.
  3. Remove the screws holding the mechanism in place (usually attached to the trim). Remove the screws holding the crank to the window, and any others that may be attached to the window or trim.
  4. Buy an exact match to your window mechanism. If you can’t find one, you’ll need a professional to install a different mechanism and likely rework your window.
  5. Line the new crank up with the old holes. Screw your crank arm and casement cover into place. If the hole is stripped, a couple of wooden toothpicks can provide good grip and easily solve the problem.

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Replacing It, Part 2

Now, this is where things can get slightly tricky. If your old crank handle spins when turned or can’t pull the sash far enough to engage the lock, you’ll need to replace the crank mechanism. To do this, simply buy a new crank and reinstall it. If the operator mechanism has broken, just replace the whole operator mechanism.


  1. Disconnect the crank arm from your guide track. Take out the screen (if you have one) and open the window until the plastic guide bushing aligns with the track notch.
  2. Look for trim screws inside the screen track and remove them and the casement cover. If it’s not attached with screws, there are likely nails or staples holding it in place. Use a utility knife to pry the casing up, if this is the case.
  3. Close the window and lock it until you have your new crank.
  4. Install the new crank (usually just a matter of screwing it into place).
  5. Test the new crank.
  6. Success!

Other Common Window Problems

If you’ve just replaced your window mechanism and have found that it’s still not opening, there could be other causes. Take a look at the following issues and fixes to ensure they’re not affecting your window.

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Cracked, Warped, Rotted Wood Frame

This is a common issue with wood window frames. If you only have a plastic frame, you’re likely free from these issues. (Hence why plastic frames are increasingly popular now.)

If you do have a wooden frame and the window suddenly won’t open, chances are it’s warped or cracked. This will prevent your window from opening, and generally be a hassle. To fix this, you can do one of two things:

  1. After replacing badly damaged wood, use epoxy wood filler to fill cracks and smooth edges.
  2. To prevent damage, regularly repaint your windowsill. This will provide a barrier between the wood and any moisture, as well as UV damage.

If you’ve been regularly repainting your sill, there’s another issue that may pop up – you could have inadvertently painted your window shut!

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This is only a likely cause if you’ve recently painted. That doesn’t necessarily mean yesterday, but recently enough that your paint may be still drying. If this is the case, it’s entirely possible that as your paint dried, it formed a seal against your window. This is why we tape things off when painting!

To fix this, you’ll need a utility knife, and potentially a hammer and sandpaper, depending on the damage. Now:

  1. Begin by running your utility knife along the paint seal. This will hopefully cut the paint and solve the problem.
  2. If you can’t move the window after doing this, you’ll need to work a bit harder.
  3. If it won’t move, pry window stop from the side jamb with a hammer to remove nails.
  4. Try again to lift the sash. If it still won’t move, repeat step 3 on the other side.
  5. Remove the sash from the window frame and sand off paint that’s still stuck. Prime and repaint the window – with the window open and taped off.

This isn’t incredibly common, but I’ve seen friends replace an entire window mechanism (like above), only to later realise they painted their window shut!

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Window Won’t Shut

Okay, you’ve checked that your frame isn’t warped, cracked, or rotted, but it won’t close. There are four things you can do to fix this: clean the window track, straighten the window, lubricate the track, or tighten the fasteners. Let’s break that down a bit.

Cleaning & Lubricate the Track

This is something you should be doing anyway, silly! Make sure your window track is clean, otherwise it won’t open. Clean it with a brush and damp rag, vacuuming up serious bits of grime.

Once that’s done, you’ll want to apply some lubricant to the track. You’ll be able to open it much more easily and this can be done with a variety of materials. I usually use WD-40, but I’ve heard beeswax or candle wax as a solution, as well as silicone spray for composite windows.

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Straighten the Window

If the window itself is off-centre, you can try to recentre it. This is an incredibly unlikely scenario, but I’ve seen widow frames get knocked off-kilter before, so I may as well mention it – right? You can push and pull on the window frame, but short of removing it and realigning the window, there’s not much you can do here.

Tighten the Fasteners

This is an oft-overlooked issue with windows that won’t shut. Sometimes the fasteners holding the frame in place can loosen up. This is an easy fix – tighten them! If the hole itself is loosening, you can use the toothpick solution (mentioned above), or fill the hole with wood filler and then replace the fastener.

Final Thoughts

A window mechanism that’s broken isn’t the end of the world. They’re easy to replace, usually taking no more than an hour or two. And the best part? You get a new window mechanism out of it! While it’s entirely possible to replace single parts that are broken, I recommend simply replacing the whole mechanism. This will allow you both a better look and a functioning window crank. Alternatively, you can inspect your window to ensure something else isn’t at play.

If the window won’t open, check for cracked or warped wood around the frame. Another possible cause of a window that won’t open is that it’s been painted shut! This is not entirely common per se, but it can happen. Finally, if your window won’t close, it’s entirely possible that a good cleaning and lubrication will solve the issue. You can also tighten the fasteners or even straighten the window, though that last one is a bit of a hassle. If you’re still having issues with your window, it’s time to call in the professionals. They’ll get the job done faster and better than you likely will, and you’ll end up with a well-installed, functioning window.