Is this a known issue? Is the power supply just toast? (Is it even worth it to replace at this difficulty?)
Yep. Yep. Nope.
I'll buy your base plate though.......

I have a spare base connector board from an S2 I had that was never able to reach 1 TH. I thought the connector/power board was the issue, but apparently it wasn't. I'm in Montreal, so you'll have to decide if shipping/customs is going to be worth it to you.
I just sent you a PM!