If your mortise cylinder is sinking into the door, it is likely due to wear and tear or damage to the door material or the surrounding structure. Mortise cylinders are the type of key cylinders commonly used in exterior doors, and they are installed in a recessed pocket or "mortise" within the door.
Here are some potential reasons why your mortise cylinder might be sinking into the door:
Wood deterioration: If the door material is made of wood, prolonged exposure to weather elements, moisture, or termites can cause the wood to weaken or rot. This can result in the mortise pocket becoming less stable, causing the cylinder to sink.
Improper installation: If the mortise pocket was not cut to the correct depth or if it is too wide, the cylinder might not sit securely, leading to sinking over time.
Loose screws: The screws holding the cylinder in place may have become loose, allowing the cylinder to shift and sink.
Door misalignment: If the door has shifted or become misaligned over time, it can affect the stability of the mortise cylinder.
Repair or replacement options will depend on the extent of the damage and the condition of the door. Here are some steps you can take to address the issue:
Tighten screws: Check if the screws holding the cylinder in place are loose. If so, tighten them to see if that solves the sinking issue.
Evaluate the door condition: If the door material is damaged or deteriorated, repair might not be possible or cost-effective. In such cases, replacement of the door or repair by a professional carpenter could be necessary.
Fill the mortise pocket: If the mortise pocket is too large, you might be able to use filler material (like epoxy or wood filler) to rebuild the area around the cylinder, providing a more stable base for it.
Consult a professional: If you are unsure about how to proceed or if the damage is extensive, it's best to seek the advice of a professional locksmith or a door repair specialist. They can assess the situation and provide the most appropriate solution.
Ultimately, if the sinking issue persists or if the door material is significantly compromised, it may be safer and more practical to replace the entire mortise cylinder or even the entire door, depending on the severity of the damage.