Extension Spring, Crescent, TOSTEM, LIXIL, Shin Nikkei, Window Lock, Spring, 3 pieces

This is a replacement spring for the crescent lock used in aluminum sash windows built around the year 2000.

The original spring broke, causing the lock to lose its springiness. After searching extensively, I found a spring that fits.

I am listing this product because I believe others may be looking for a similar replacement.

Here are some reviews from previous buyers:
It worked perfectly for raising and lowering the lock.
Many people have purchased this item.

Review from a buyer in July 2025:
It worked perfectly for raising and lowering the lock.

We have also received reports that it fits Shin-Kagaku sashes from around 1990.

Photo descriptions:
Photo 1: 3 springs that will be sent to you.
Photo 2: My own window lock (crescent).
Photo 3: Inside the lock, showing the broken spring.
Photo 4: Left: Broken spring. Right: New spring.
Photo 5: Lock with the new spring installed.

Instructions for replacement:
Photo 6: Use a small flathead screwdriver to gently pry open the lock and loosen the screws. Loosen both the top and bottom screws slightly.
Photo 7: Remove the top screw, move the lock slightly, and then re-insert the screw into its original hole, but not so tight that it falls out.
Photo 8: Remove the broken spring and install the new spring. The spring can be installed in either direction.
Then, reassemble the lock by reversing the steps.
Please be careful, as screws are easily dropped.

Quantity: 3
Wire diameter: 0.5mm
Outer coil diameter: 3.7mm
Free length: 18.7mm
Spring constant: 0.765N/mm
Material: SWP-B (a type of piano wire)

Additional springs are available for ￥155 each. Please leave a comment.
We also have a 10-piece set available.

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