Repairing the lock
If your lock isn't locking/unlocking when you turn the key, look at the bottom of the lock barrel.
There should be a little ~4mm diameter cylinder protroding from the base that inturn fits into the slot in the metal locking piece.
When the key is turned this should move the metal and lock and unlock the boot. In our case this has sheared off!
To fix it we need to drill a hole, tap a thread, and fit a short M4 bolt.
First of all take a 3mm drill bit and carefully drill a hole right in the centre of the circular mark left by the sheared off cylinder. Carefull not to go too far or you will damage the lock pins. And don't leave the key in the lock barrel whilst you do it or you will drill your key!
Next get an M4 tap and thread some turns into the hole, again don't go too far but you want about 4 good thread turns for the bolt.
Here is my lock with the hole tapped.
Next you need to fit an M4 bolt. First of all put the key back in the lock, you will see it in your new hole. You want to fit the bolt as far in as possible without fouling the key but not so far out it will break out. I reckon about 4 turns.
Next you need to super glue the bolt into the lock. Take the key out first (you don't want to glue it in to the barrel!) Put glue on the thread of the bolt and screw it in 4 turns, bead some more glue round the bolt. Be careful not to drip glue inside the lock or you will glue the lock pins shut and you'll ruin the lock.
Super glue likes warmth (>10C) and takes 24hours to reach full strength, so bring it inside and leave it over night.
Once the glue is dry you need to cut the head off the bolt with a hacksaw. I cut mine a little to short about 4 turns, it works but it would be better with about 6~8 turns of the bolt.
The bolt is a little tight in the metal locking piece's slot, so file it down until the fit is snug yet free moving, and
make sure you smooth off all the rough edges.
And that's it all you have to do is reassemble everything in the reverse order you took it apart. Hey presto! A smooth working lock and most importantly the same key!
Hope you find this useful!