A few things, my door handle does not have a spring any longer, and works fine. When the door tries to unlock does it sound like a grinding noise? Because you Door Lock actuator might have finally given up the ghost, it is a pain to replace, but once you understand how everything works in there, it is quite easy. But to be honest, it sounds like it is binding up, due to lack of lubrication. WD40 will work to help you figure out if it is an issue, but I suggest something that will work a little bit longer. Also the rivet that Koda2000 is talking about, can easily be replaced with a nut, bolt, and washer, if that is even the issue. but either way that is what I did, and I have had no issues, even though some people go all crazy and say it needs to be a rivet...
Good luck man, I have been down this road many times, at first it stinks to figure it all out, but once you understand it, it's straight forward and easy.