Driver's side door has been hard to open with the key for some time. The other morning when it was so cold the lock broke and turns freely to the left and right. I took the panel off and when I touched the round plastic piece on the rear of the lock it fell off. It is attached to a rod coming from the bottom of the door. I am told this plastic piece may be broken since it should be held on the lock by the c clip. Not sure this is correct but I do not have a diagram. Where can I get this plastic piece or will I have to buy a complete assembly and if so, what do I ask for that will include the plastic connector? Thanks