My driver's side door lock has been difficult to unlock since I acquired the car. The little arm attached to the lock cylinder that fits inside the locking mechanism in the door has way too much play and I had to jiggle the key back/forth forcefully to get it to unlock.
While I had the door glass out, I cut a small piece of fuel line from an old weed-eater and slid it over the arm. It works so much better now. Easy to lock/unlock with very little force needed. I shot a little silicone lube on the outside of the hose to keep it from binding in there.
Is good, yes?