'Same problem 11 years ago with the same model 1984 300SD.
('Incredible German engineered automobile...They'll never consider making
anything so tough or simple ever again!)


The dust from the brushes tends to interfere with operation after about 150K

I did replace my starter with a set of ramps AND two VERY long extensions
(to get to the starter bolts from astern [the rear]) in my brother's garage
about 1996.)

'bought the replacement from "Pep Boys" on San Jose Blvd in Jacksonville,Fl.
A Bosch reman with a lifetime guarantee.

I'd still check out ALL the possible connections.
Even though you can swear to the starter's demise!