Hello! This looks like it could be a match for the Pella 83-123. I think this may be what you want, but please look it over and let me know if you had any questions.
I'm sorry to hear you're having issues with these parts. Can you go into more detail as to exactly what's happening? I don't quite understand what you've described. You said that the 83-115 does engage with the door frame. With that in mind, what issue are you having that's preventing the door from latching?
Ah, I think I understand the problem. Yes, there is a spring built into the door itself, specifically in a small metal box inside the frame. This is what allows the latch to be retracted and snap back into place.
The bad news is that neither the spring, nor the box that contains it, are sold separately or are meant to be repaired in any way. You could contact Pella directly to see if this is something they'd be able to supply to you, but in my experience they are rarely willing to do so. Odds are they might suggest that you buy a new door entirely.
I am sorry for the inconvenience. I really wish we could get that spring, but it's just not possible.