Central locking works on all doors except the driver's door. There is little resistance when I turn the key as compared to the passenger side and the 126s. Could be a bad vaccum line upstream of the door, but I'll try the door first.

Oval wood trim piece? So you're saying I'm far from where I should be when futz with the strip that extends to the B-pillar? I should be working on the stubby piece by the grab handle? This is oh so confusing to me and embarassing considering I've replaced cylinder heads and transmissions. A picture would be worth a thousand words in this case, but thanks for the detail.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD