First Check for inoperative lock
 

Today, I am unable to turn the driver's side manual door lock. If I hit the central lock button in the console, the passenger lock closes and the driver's lock moves slightly, then the passenger lock pops back up.

I can put the key in the door handle and turn it easily, but central locking doesn't even try to engage.

I don't see any blown fuses at all.

Before I start removing stuff from inside the door (as indicated in the Bentley manual), are there any typical steps to check first?

i would pull the door panel and take a look. there are some rods in there, may be plastic, that can come off/break.
i had to "wire" one back on on my 930. i have the part for next time it fails.

While you are there, I would also look for a white wire, it may have severed and causing a short.

Over time, if it dislodges and sit on a moving part, it will rub off the lining and then short it out. When it grounds out, it will default open.

It's obviously some mechanical obstruction. I slammed the door one good time and it lock and unlocks easily. I'll have to take a look and see what is hanging it up so that I don't end up having to crawl in or out of the passenger side if it sticks in the locked position.

Bangin' it hard was the first step listed in the Bentley manual?