Well, I owe you guys a photo. I found the problem. Turned out to be the diode pigtail.
Just like the photo Rob shared, the diode leads are uninsulated, and I found mine laying on top of the radio chassis shorting out.
The diode was not broken in half, but did exhibited some thermal trauma.
So it all adds up now. Blown fuses over bumps, buzzer going off when it shouldn't, and a quick wiggle of the harness always seemed to fix it.
Should be a quick fix now.