i just bought a 1980 mercedes (1994 engine) 300 td wagon about 6 weeks ago; the previous owner ran it on diesel, biodiesel, and straight vegetable oil, but i've only put diesel in it. it had been running beautifully (including on a long road trip) until it started having trouble starting a couple of weeks ago. i'll try to find the right topic area to post my question-we've ruled out a lot of the common starting problems, but being new at working on mercedes, thought we'd turn to the experts.

thanks!