This explains how to replace the lock on a Givi hard motorcycle top/side case. The specific model shown is an E55 Maxia 3 with the tail light kit installed. You might want to do this because you bought your top case and side case separately and would like them to use the same key, or because you've lost the key to your case. Givi doesn't seem to sell replacement keys, but they do sell replacement locks at a reasonable price ($10 each or $30 for a matched set of 3).
You'll need to have the case open to do this. If you've lost the key, your options are picking the lock or drilling it out. Givi recommended a 1/4" drill bit, but I opted to not drill the lock out. A locksmith should be able to open the case.
Step 1: What You Need
You'll need a new lock. The kit comes with a pair of keys, a new lock cylinder, a surround (housing for the lock) and a circlip.
You'll need a Phillips screwdriver. A small flat screwdriver or something of that shape will help with the circlip, but you may be able to do without it.
If you have the tail light kit installed, you'll need a 2.5mm hex wrench.
Step 2: Remove the Tail Light Plastic Insert
If you have the tail light kit installed, you'll need to remove the plastic insert that holds the contacts on. You'll need to remove two screws with a 2.5mm hex wrench.
Step 3: Unscrew the Back of the Locking Assembly
There are four Phillips screws holding the locking assembly on. Unscrew them.
Step 4: Remove the Locking Assembly
It should just pop out of the case, now that you've removed the screws.
Step 5: Remove the Circlip
Remove the circlip from the back of the old lock cylinder. The latch should now be removable. There's a ball bearing behind the latch. It'll probably fall out at this point. Try not to lose it. The old lock cylinder should now slip out of the front of the surround, and the surround should slide out as well.
Step 6: Replace the Surround and Lock Cylinder
Slide the new surround and lock cylinder into place from the front of the lock.
Step 7: Replace the Latch and Circlip
Be sure to put the ball bearing back into place.
Make sure the lock is in the open position and replace the latch in the open position. Or make sure the lock is in the closed position and the latch is in the closed position. Your choice. Press the latch firmly into place, so that you can see the groove in the end of the lock cylinder. Slide the circlip into the groove.
Step 8: Test the Locking Mechanism
You should be able to open and close the lock. The press to open button should release the catches at the top of the lock (that would hold the lid of the case in place), turning the lock past the open position should release the handle. The latch should move between the open and locked positions.
Step 9: Reassemble
Put the locking assembly back into place, adjusting the gasket as necessary. Make sure the release button hasn't fallen out and slid under your workbench. Replace the four screws on the inside of the box. Test the lock again. Replace the two hex screws on the plastic piece for the tail light contacts. Enjoy your new lock.