The type of mortise lock key needed depends on the specific brand and model of the lock. Different brands and models of mortise locks require different types of keys, such as standard keys, skeleton keys, or specific proprietary keys. It is important to identify the brand and model of the mortise lock in order to determine the correct type of key needed. If unsure, it is best to consult the manufacturer or a locksmith for assistance in identifying the correct key for the mortise lock. **

The mortise lock may be stuck due to a variety of reasons, such as a buildup of dirt and debris within the lock mechanism, a misaligned strike plate, or a malfunctioning internal component. Additionally, the lock may be stuck if the key is broken or if the lock is damaged. It is important to carefully assess the lock and identify the specific issue in order to effectively troubleshoot and resolve the problem. **

The key may not unlock the mortise lock due to several reasons. It could be that the key is not the correct one for that specific lock, or the key may be worn out or damaged. Additionally, there could be an issue with the internal components of the lock, such as a malfunctioning cylinder or pins. It is also possible that there is debris or dirt inside the lock preventing the key from turning properly. **

A universal key that fits into a mortise lock is typically a skeleton key. This type of key has a cylindrical shaft with a series of teeth of varying lengths, allowing it to fit into different types of locks, including mortise locks. The design of the skeleton key allows it to manipulate the internal mechanisms of the lock to open it. However, it's important to note that using a universal key to open a lock without proper authorization is illegal and unethical. **

The security of a mortise lock in an old door depends on various factors such as the condition of the lock, the quality of the materials used, and how well it has been maintained over the years. Generally, mortise locks are known for their durability and strength, making them a secure option for many older doors. However, if the lock is worn out, damaged, or not functioning properly, it may be less secure. It is recommended to have the lock inspected by a professional locksmith to ensure its security. **

The length of the bolt in a mortise lock should be appropriate for the thickness of the door it is being installed on. If the bolt is too long, it may not fully extend or retract properly, leading to issues with locking and unlocking the door. On the other hand, if the bolt is too short, it may not provide enough security. It is important to ensure that the bolt of the mortise lock is the correct length for the door it is being installed on to ensure proper functionality and security. **

It seems like you may have incorrectly aligned the lock body with the mortise pocket in the door. This could be causing the lock to not function properly. Additionally, you may have not properly secured the lock body to the door, leading to instability. It is important to carefully follow the installation instructions provided with the lock to ensure proper functioning. **

The security of a mortise lock in an old building door depends on various factors such as the condition of the lock, the quality of the materials, and the installation. Generally, mortise locks are considered to be more secure than standard cylinder locks due to their design and construction. However, if the lock is old, worn out, or poorly installed, it may be less secure. It is important to have the lock inspected and maintained regularly to ensure its security. **