First you need to rotate the latch so it will latch when you close the drawer or door.
- Remove the screws from the solenoid cover. (One of mine was hidden under a sticker.)
- Remove the E-ring ring that holds the latch slug in place. (It's kind of hidden between the spring and the square brass collar.) If you don't have the specific tool from removing these, you can usually pry it off with needle-nose pliers and/or a screwdriver.
- Rotate the latch slug 90º so the long square side is on the side of the lock with the mounting holes.
- Replace the E-ring and screw the cover back on.
The lock solenoid needs to have enough spacers behind it so the latch will clear the frame when the drawer is closed so the latch will lock.
The latch also needs to be able to move freely when the drawer is closed. The solenoid isn't super powerful, and if it's wedged too tightly it won't retract when activated. You will probably need to add add some spacers between the lock and the drawer/door.
Position it vertically so the latch smoothly slides under the drawer frame and fasten it in place with #4 wood screws. Drill pilot holes for the screws so the wood doesn't split.
The knock sensor needs to be fastened somewhere out of sight, but where you can knock easily and clearly on the other side. For a door that location is probably on the inside of the door. For a drawer it can be inside of the face of the drawer, along the side of the cabinet or under the surface of a the desk.
Wherever you put it you'll probably want to be able to reach the programming button.
Use 1/2" #4 wood screws to attach the perfboard to the inside of the sounding surface. Attach it so the piezo is against the knocking surface, and carefully tighten the screws to hold it in place. Reinforce and stabilize the perf board with some spacers of scrap lumber. (I used a bit of 1/4" (6mm) square dowel between the perfboard and the drawer face, you can see it to the left in the picture below.)