It's a common problem and there are various bits of info scattered around the web, but I never found a picture of how to fix this, so I thought I'd take one.

Symptoms: interior door handle either just waggles a bit or doesn't move, usually driver's side. Car will not unlock or lock properly on c/l, just cycles repeatedly. Cannot open the car from inside with the affected handle.

The problem is the little spring inside the locking mechanism which breaks and falls off. When it does, the locking just doesn't work right. So Mr Haynes tells you how to get inside the door and remove the unit, but doesn't tell you what next. If you are lucky like me the spring drops into the door skin. Find it, bend a new loop, and re-use it. I cleaned everything up with WD40, didn't relube. I think the gungy white lube ford used is part of the problem, as the spring is a bit feeble and a stiff mechanism will overwork it, maybe contributing to the failure.

So anyway, here is a picture of what you need to do with the little spring, then it will all work properly again:



It's a good move to go around the car and lube all the other door catches, just blast with WD40 and wipe any accumulated dirt off.

Hope that helps in the future for anyone who comes here searching