When I operate the switch for the driver's window on the 116, the motor spins for a second before it engages and begins moving the window. Happens on both up and down. Is this a quirk to be tolerated or a sign of impending catastrophic window failure?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

How do you know the motor is spinning first?
It sounds like there may be a missing tooth on the gear.
I don't know if the motor is the same on your model but this has a picture that I posted of the motor in mine and it may help.
Replacing window motor?

__________________
1983 300SD
200000miles

I can hear it. No nasty sounds, I can just hear the motor start turning before it engages anything.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

If yours is the same as mine its not hard to take apart so you can look at the gears. It sounds like the shaft is slipping in the center of the large gear but you won't know until you take it apart.

__________________
1983 300SD
200000miles