locking handle damaged
Rob
Thanks for reaching out! Your handle set reminds me of our 82-090 Legacy Handle Set. This set is available in the satin nickel color you have. The internal mortise lock looks a lot like the 82-260, which is sold separately.
To confirm that these are the correct replacements, carefully look over the dimensions below and compare them to your handle and mortise lock.
You may also want to consider replacing the rollers on the patio door as well; at the very least, cleaning the track. If it is hard to open and close the door, it could be because the rollers need to be changed. Having to put added force on the handle set due to the friction from the rollers could be causing the handle to loosen.