I have two fans set up on W140 and pass. side fan was making noise and did not spin as easy as driver side fan. According to WIS, to remove the fans on W140 radiator and condenser have to be removed with the fans as an assembly. That would require freon recovery and recharge. I did not want to do that.
What I found was that fans could be taken out without disturbing condenser and radiator. There are a few small bolts hard to access, but still better then WIS process. Also the fan shroud needed to be trimmed in the lower driver side corner to clear condenser feed line.
When the fans were removed I found a big pile of leaves, dead bugs, etc. behind and below pass side fan. This pile was covering about 10 - 15% of the condenser area, and not visible from outside. So do clean your condenser!
As for the fan, I lubricated outside bearings with a few drops of ATF. That made it spin better for now. The inside bearing is not accessible without full disassembly. I'd wait for the cold weather when car can live with the single fan and then try to take bad one apart and see if it could be fixed.
Mike