'98 Quest :: Door Locks Seized -- Any Suggestions??

[crosis]

Vehicle: 1998 Nissan Quest GLE

The previous owners apparently never used the door locks to unlock / lock the doors and so when i go to insert my key into any of the 4 locks (driver side, passenger side front and side, rear hatch) i am unable to turn the locks. The key inserts fine but i cant turn it to unlock / lock the door. I am forced to use the key FOB.

Is it a fairly simple procedure to extract each lock cylinder from the door so that i may open it up to free up whatever is sticking in these locks? I want to get these locks working again. I am open to replacing all these locks but have no understanding of an automobile's locking system and tumblers unless it is the same as a house door lock.

Thanks for any tips. For the record i purchased some CRC lock deicer / unseize spray (it had graphite) and sprayed into the locks. No surprises it did nothing for me.