Mechanic noted today my '01 SLK 230 needed idler arm replacement in addition to the starter. (passed virginia emmissions!). He also noted that the engine ground strap was 75% corroded through. Had no problem finding quality parts except for the engine ground. So I'm joining here to collect what information I can and remanufacture one from parts at the local hardware, and document a specification for the part and an installation procedure.