The 83 doesn't have a servo.
The way we check alternator output is by measuring the Amperage output. At home you may not have an ammeter, so you will have to rely on the voltage check. The problem is that a generator can easily put out 13volts with 2 amps. You need to have it checked with a good load capable tester.
1992 500E (very soon I hope
1981 280GE SWB
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