G'day all.

This weekend am pulling the inside skin of the drivers side door to investigate the door handle lock on the drivers side door. Locking mechanism is fine but the barrel is jammed as key only goes half way.
Just curious if anyone has had same issue and any tips or if anyone knows what to be looking for.

Should mention no electronic keys or immobiliser or anyhing. Just standard lock and key

Cheers All.

Give it a spray with WD40 and wiggle the key in and out.
Gerry

Has some kid (or x-girlfriend) jammed a stick inside the key hole ?

Not from what I could see. Was fine getting in the car in the morning. By time got to destination, it had jammed. no idea.
feels like something blocking it,

best thing for lubrication of locks is graphite dust, it may fix your problem but you can get a small bottle from supercheap or other auto stores, bout $18 for a small bottle and just blow some in there ... see if it frees up. WD or other oil will attract dust to your lock.

Reading your post, it's not 100% clear whether you mean the key will only enter the keyhole halfway, or the key enters the keyhole fully but then the lock only rotates halfway. I read it as the latter.:)

The key only is going into the hole halfway. nothing appearing to be jamming it and no visible damage to barrel.

http://t1.gstatic.com/images?q=tbn:ANd9GcRB_r40Qpr6oJAnITcu_Qw8Y5VDP_CPd iIsqPQyMbMnQ_1KGzMTaVUjn8qu3w

Here you are - the inside of a lock barrel.

The pins are spring loaded and pushed down by the key as it enters. If one of the pins is jammed through dirt entering, or being bent, it will stop the key from entering. Most car barrels will strip down to the point where you can see the pins and assess the problem. If it is jammed through dirt, give it a squirt of degreaser, and work the key in it gently. Once freed, dry, lubricate with a non sticky lubricant like graphite, and reassemble. If the pins are bent or the barrel is damaged, you need a new one from Mitsu or a wrecker, and a locksmith can set it up to work with your key. Finicky work though.

Went through this with an older Mitsu, I hope the barrel design hasn't changed too much. lol