I am looking to find out what the setting is for 18-20lbs of preload on the secondary spring. It is the beige spring. Any help would be great.

Here is a list of the preload at each position using the beige secondary spring. Values for other springs will be different, however, the relative change from each position will be the same. Also, if you spring is weak, then adjust accordingly.
You should measure to make sure you have the correct
preload.

Hole Lbs
C3 2
A3 4
B3 6
C2 7
A2 9
B2 11
C1 12
A1 14
B1 16
C6 16.5
A6 18.5
B6 20.5
C5 21
A5 23
B5 25
C4 26
A4 28
B4 30

Thanks gunner.