Any photo or PN for the spring?
Is it this? https://cdn.instructables.com/FPN/57Z0/HW8SWS3T/FPN57Z0HW8SWS3T.LARGE.jpg
It's a frustrating job only because the limited space makes getting the latch out and back in is very tight. Replacing the spring is a simple task. Take pictures as you go along. Most importantly, pay close attention to the angles that allow you to get it out so you won't fight as hard getting it back in. Once done you'll probably never have to deal with it again. The alternative is using the key to open every time you want in.