Look. I have a 2006 sprinter with 440,000 miles. I fixed my leaking injector at 435,000 and its been leaking since 370,000. Clean out the large deposits of crud, soak the injector with wd-40 and leave it for a day. Come back the next day and put some acetone on it. After that unscrew the fuel lines to the injector. After you unscrew all the lines unscrew the retainer screw take out the retainer. Yes you can take out retainer before you take out injector. Once retainer is out take a large flat screwdriver and pry UNDERthe threaded fuel line to try to move inector side to side. If your replacing injector then you can pry against the thread. Once injector is out clean the seat of the injector with acetone (ect) and take out the copper washer. If your washer is stuck, find a flat head screw driver that doesnt fit inside the washer. Insert screwdriver inside injector hole and try to move the washer. If that doesnt work then find a flat screwdriver that fits in the washer and tap it down a bit, and try to turn. The washer will not fall inside the engine. Dont worry. Once removed washer, clean off injector or replace the injector and apply a coat of antiseize to injector and the hold down screw. Fit everything back into place and put back hoses, bleed engine, and there you go.