Loud Noise around Alternator

[Vereeken]

Gents,

Looking for your idea's on where to search (82 SC ROW).

The problem is related to the hot air blower in the motorcompartment.

Car not running, ignition on, 12v found at blower connection.
Car not running, ignition on, blower on 12v found at blower connection and blower blowing with no noise other then some normal whine of a elec. motor at full speed.

Car running, blower on, volts all over the place at the blower connection, blower not moving at all and terrible noise at (seemingly) back of the alternator. Noise resembles marbles that somebody is shaking in a can.

Had the alternator out and checked by a Bosch test=center. Voltage and amps perfect and very strong, bearings excellent, regulator ok. They had the alternator up to (equivalent)8000 rpm and no noise. They gave it back and do not want to overhaul it as nothing is wrong.

Any suggestions on where to look?

Much appreciated.

Michel