Maruzo,
It isn't worth the time to rebuild the regulator, just buy a new one. It is much easier to replace (4 bolts) than trying to rethread the cable (it's spring loaded) while rebuilding the regulator. The new regulator will come pre-lubed ready to install and they are not that expensive. Don't bother with the BMW brand, they are way overpriced. I have typically paid about $60 or less for the couple of regulators I have had to replace. So far I haven't replaced the same one twice so I guess that speaks well of the quality of the lower cost ones. Oh, by the way, each regulator in your car is different, parts not the same.
AceEngineer
