In the time you've taken to post repeatedly, you could've soldered every joint on the analog board.

You've been given lots of good advice, why not take it? Solder -- don't just "reflow" -- the specific connections that have already been pointed out to you. The yoke connections are the first things to take care of. If you read the classicmac2.pdf doc, you will find advice that these connections should be resoldered whether or not you can see anything wrong, along with explanations for that advice.

The symptoms you describe are pretty common, and the likely solutions are well documented.