Why do we need K1 and K2 springs?

[xweezyx]

So the info is out there on how to replace these and what they fix. I just got a 190D that I've nursed back to health and only need to get rid of the 2-3 and 3-4 flare, but I have a few questions that I haven't been able to find answers for.

What exactly happens when the flares start and a new K1 is needed?

Does the spring itself wear out?

Is the new spring revised?

Does it compensate for other wear in the transmission? a band-aid per say?

There is way less talk about the K2 spring for 3-4. Is it less likely to fix this?

These questions are for my mechanical curiosity and so I can sleep at night until my springs come and I can service the trans. Thank you.

(btw, Ive disconnected vacuum to the modulator. I get a clunk AFTER the flare when it goes into gear. I don't think vacuum is my problem )