Gene,

You raise two good points, but on the first one...

"When checking the output at the alternator itself, to identify a working alternator whose current is lost on its way to the battery, one MUST use the alternator housing as a test point on a Volvo. The rubber mounted alternator needs a separate ground wire and they CAN fail or get dirty mountings.

...I believed I was on "safe ground" when I had asked about the warning lights with Key ON. Since the answer was that they were On, that seemed to confirm the ground path to and thru the alternator and it's ground wire as a basic test. To make sure, I asked for a test with D+ disconnected—but got no reply.

We hadn't yet gotten any voltage checking responses, where double-checking to case ground might have been indicated, depending on the reported readings.

But thanks for the belt tip and how it can cause poor charging when bulb indications are normal. I would not have thought of that.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.