Atrium door lock

A quick learner from USA says:
I have an Atrium door lock/mortise on my wood atrium door that opens INTO my family room. I notice last winter that the lock was difficult to turn, and at times when the handle was depressed door would not open because dead bolt was stuck. I managed to loosen things with some WD-40 this past summer, but I was wondering if you could tell me what you thought the problem might be. Should I replace the entire lock set/lever, etc. or is there a part I can order that would rectify the problem. I know I would definitely want to purchase a new lock because I cannot locate the key.

Prices to replace parts? Entire lock set?
Thanks for your help
I can measure if you would like me to. FYI...brass hinges on RSF are stamped 'ATRIUM'.

User submitted photos of door hardware.
Profile picture of Dave Sr.
Dave Sr. from SWISCO responded:
Based on your description, it sounds like the problem lies with the inside mortise lock. The handles themselves are probably fine. After a while, the mechanisms inside the lock start to wear out, especially the springs.

Now, I'm not sure exactly what mortise lock it is you have. Many storm door lock sets don't have their mortise locks supplied separately, unfortunately. You may need to replace the handle set regardless. I would start by looking at our 82-400 handle set. This might match what's on your door now, but look over our information to confirm.
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