Ok. So, having done this now I'm going to add a bonus tip.

When reassembling, make sure you deal with all the connections (courtesy light, ashtray etc) EXCEPT for the door lock plunger. Make sure that this doesn't line up with its hole. Get all occupied with the catches lining up, and just ignore that plunger.

Then, when everything's back together, note that the door handle is acting funny. Now is not the time to think! Just slam the door closed to see if that helps.

Now the door is locked and there is no way of unlocking it because the threaded shaft for the door lock plunger is trapped inside the door panel. And you can't get the panel off, because it needs to come up and out, and the door is closed. So it won't budge.

Swear a lot.

In the end it turns out that if you lower the window all the way and ease the panel up you can get a thin blade in there enough to wiggle the plunger shaft over and line it up with the hole and then you can thread the plunger on, unlock the door and open it.

I can't say I felt any smarter by the end of this job than when I started.

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1988 420SEL