Update. Got the amplifier apart finally and although there's a LOT of screws and things to remove, it's fairly straightforward. N8NN has a nice write up on the steps to get it apart, and that takes out a lot of the guesswork. Interesting find, my VP-1000 doesn't have the three 5.6Ω resistors. It has two 10Ω and a wire jumper. It looks like it could have been a factory tweak, as mine is relatively new (2012) as the Quadra goes. I called Yaesu tech support and they didn't have a record of that as a formal ECN. There's some flux residue on the resistors solder side, so it seems likely that those have been out once. The jumper didn't look just hacked in, and kinda looks like a 0Ω part. The resistors were indeed open. This is effectively a step-start. The three resistors are in series with the AC mains, and the relay coil is driven off of the +12v, so once the power supply starts, the relay pulls in and the resistors are bypassed. I have the three OEM 5.6Ω parts on their way, and I'm planning to put it back to print. I sent an email off to AB4OJ just to see if it rings any bells.