I have a 380SL that would ONLY hard start when the engine was hot/warm. Cold starts were never a problem. MB dealer said no accumulators available any longer for the car and insisted it's probably leaking injector and highly unlikely to be the accumulator (not just the parts guy but he also consulted one of the mechanics)

Well to make a long story short, I found a new accumulator (IDENTICAL in every respect to original including manufacturer logo), installed it and have had no cold or hot starting issues since. NOTHING else was replaced (not the filter nor any fuel lines).

I don't know if this will solve your problem but it solved mine. Good luck.

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Jim