In case anyone is looking for a write up in addition to the above good info on injector rebuilding/replacing, take a look at the link below. If you have any additional questions, feel free to post a Comment just below the article and we'll do our best to give you specifics.
Mercedes-Benz W124 Fuel Injector Replacement | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article
-Dmitry