Anyone ever disassemble a distributor - need help

The springs and the plates work together to provide the curve.
If you change springs may (likely) need to adjust the spring tension.

The tension on the light spring determines the rpm the advance begins.
If it begins below idle speed, it will drive you nuts.
If its too delayed, performance off the line will be hurt.

Tension doesn't apply to the secondary spring. But with it, the same adjustment to the anchor as used to adjust tension controls when the heavy spring slows down the advance. This is the critical part for good part throttle performance with vacuum advance, and also mid to top end timing.