There are 4 terminals on both -the upper or lower layer
I believe the wire colors/term. Arrangement is:
L - upper BROWN
1 - upper PURPLE
2 - upper NC
3 - upper NC

L - lower BLACK
1 - lower NC
2 - lower GRAY
3 - lower BLACK

Is this correct? (OR - are both BLACK wires on the lower level @ [L] & [3]?)

There is no set pattern or diagram for these switches. You need to get the same switch and put it back the same way.
Other than that it is trial and error I'm afraid.