Just a guess here ...
I had a similar recent issue on my driver's door. It turned out the problem was with the cable from the inner door handle goes to the DLA. The cable sheath attaches to a plastic bracket built into the DLA, while the cable pulls the mechanism. The failure in my case was that the plastic bracket had cracked pretty severely. The result was that the inner door handle did not work at all, and the outer door handle only worked when pulled a little further than normal full travel, and even then only sometimes.
RussianBlue had sent me his old DLA (with perhaps some minor issues), and I noticed the beginnings of similar cracking on his old unit. So I did a repair on that, installed and that problem was fixed (still have some other minor issues).
So the summary is to check for that bracket where the inner door handle cable's sheath attaches to the DLA. Reinforce if necessary.
I plan to make inspecting and reinforcing that part a standard step whenever I open up a door. EDIT - and to be clear, of course "open up a door" - I'm not talking about opening a door, like every time I drive. I'm talking about taking off the inner panel, removing components, etc. So more of a bi-weekly thing.
