Not charging

NOTE EDIT on jumpering field

I would not necessarily believe a store "tester." On the other hand rebuilds CAN be shakey. You should learn to make some tests of your own ON THE CAR. That way you can get an idea if it's wiring, alternator, or regulator.

Intermittents are VERY difficult to run down. You have a voltmeter and not an ammeter? Guessing from your post you were posting voltage readings?

I "roughly" group the charging system into sections:

1 The alternator as a component

2 The regulator as a component

3 The output charge wire circuit, including the wiring from the alternator, through the bulkhead/ fuse link, ammeter, and back out, to the battery

4 The regulator power and alternator field wiring circuit

5..In rare cases, the battery itself can give trouble.

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Start by going over connections.......Battery ground to engine and ground(s) from engine/ battery to body. MAKE SURE the VR is clean, grounded, tight!!

Next, do a "full field" test. Several ways to do this. EDIT Start by disconnecting the green field wire at the alternator, hook a "clip lead" to the alternator terminal just unhooked, and jumper it TO GROUND. EDIT Start and run the engine watching ammeter/ voltmeter. Hook a multimeter to the battery and monitor it. Keep battery voltage below 16V

Slowly bring up engine RPM. Voltage should go over 14 pretty easy. Turn on loads, lights, heater, whatever. Bring up RPM a bit more, it should "keep up."

This is just a quick test. Look for the meter jumping around, which indicates a poor wiring connection or poor brushes contact