Charging issue that has come up

Recently, I went to fly my RV-6 and the voltage on the GRT EIS showed 12.2. Normally it shows 14.3. I took off the alternator and took to the auto parts store where they thought it was bad. I bought a new one and replaced it, but no luck. I checked voltages at the alternator battery connection. 12 volts when the switch is on, 0 when off. I tried bypassing the voltage regulator by connecting the field wire with the “A” connection. Then I get 14-15 volts at idle. But connect it back up and back to 12. If I turn on the lights, avionics, I see a drop in voltage as expected without the charging system working. I replaced the voltage regulator and no change. I checked with the builder, and he said he removed the zener diode for the over voltage protection as it malfunctioned. I have tried most everything I can think of. Open to suggestions.

Low Voltage

I just developed same problem. 12.9 volts. Started with new battery, but not the problem. Did you resolve your problem?

VR issue

Seems like the voltage regulator is not working right or one of the wires has come loose. What kind of VR is it? Can you check the other end of each wire?

When you mean "A" connection, what are you taking about? The system voltage, i.e the "B" output as in this attached diagram...?

Also seems to me its a loose wire or a bad switch since attaching the field (IGN in the case of these internally regulated alternators) directly will fix the issue. Although, I'm wondering if a bad wire or switch on the "field" wire would cause a voltage drop and increase alt output.