Nice photos.
This is how I re-assembled my switch (note, the instructions here do not treat the incandescent bulb parts, since I am mod'ing the switch for LED operation):
The parts. Note that the third part from the right is the metal "top hat" and I already dropped the top hat into its associated large spring (which you can't see from the angle of the photo; you can see the spring in step 3 below).
Step 1, drop the shorter, fatter white plastic piece into the appropriate half of the switch housing.
Step 2, put in the large spring and the metal "top hat" piece.
Step 3, drop in the longer, skinnier white plastic piece. Put the brass washers inside. Then put in the brass "top hat", brim end down.
Step 4, add the skinny spring.
Step 5, carefully mate the two halves of the switch together. This time, I added some clear tape to secure the two halves.
Step 6, add the ground strip, the square nut, and the "grub" set screw. I snipped the ground strip short in this photo. Normally, the strip is much longer -- perhaps 3 inches or so.
Step 7, drop the switch back into the top of the Mag body. The switch will drop down to the "ledge" or stop inside of the body.
Step 8, secure the switch with the retaining ring.
Step 8, tighten the set screw and then re-install the rubber button cover. The set screw bears against the indent on the opposite side of the switch button opening in the Mag body.
The incandescent bulb parts that I've ignored.
I'll probably connect the Mag switch leads seen in step 8 above to this driver, an SOB1000. Switch + goes to the center anode and switch - goes to the ground trace ring.