Isuzu Rodeo Tailgate lock problem

I just bought a '95 Rodeo and like an idiot was so caught up in the great shape and appearance that i didn't check the tailgate lock.

PROBLEM: I can't get the key in more than 1/2 way. I tried graphite lube but to no avail. I am thinking there is something stuck in it.

HELP SOUGHT: How can i get in there to check it out. I don't even know how to remove the plastic panel?
Perhaps me playing with this is not a good idea?! Is it tricky? Anyone done this before?

It would be really nice to be able to lock my vehicle!!

Any help is appreciated. Thanks.

http://www.automotiveforums.com/vbulletin/showthread.php?t=395073&highlight=tailgate+lock

here is a link to a 99 Rodeo.

Yes you need to get the rear pannel off.