Which part?

Hello,

Thanks for posting! It does not look like your photos were uploaded with your post. Are you able to provide photos of the hardware you are looking to replace?

Thanks for the photos! Your patio door mortise lock reminds me of the 82-260 Multi-Point Mortise Lock. To confirm that this is the right replacement, take a look over the dimension and compare them.

Alternate image for 82-260

Alternate view of 82-260