I have a 1980 euro 500SE. The distributor has two vacuum lines; one for retard and one for advance. With the engine not running, I have tested both vacuum ports using a vacuum pump. The retard side (closest to the distributor housing) holds vacuum. The advance side (farthest away) does not. Does this indicate that the advance diaphragm is faulty?
If it is, can the vacuum control unit be replaced independently of the entire distributor? Is it necessary to remove the distributor to perform this job?
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