After bleeding, if your pump doesn't work and you have to mail it off:
I had really good luck in 1983 with Diesel Fuel Injection Service
749 N 10th St
Salina, KS ZipCode Phone: (785) 825-2023
He was pretty cheap, as Salina is a very low cost place to live.
I doubt if a Mercedes Bosch would phase him at all. Lots of old tractors use Bosch pumps.