The whole reason I started this was because I had bought a faulty C64 and was trying to fix it.  The last component which I think is bad just came in - a replacement SID chip.  It appears to be working, so I can read the paddle inputs now.  When I tested the paddle inputs, I found the paddle resistors on my board are supposed to be 120K and not 120 as are on the board now.  I need to replace and test again.  I think with the serial port I'll just stick a couple solid core wires in as jumpers just to pass the test for now.  And then when everything is working I will update the gerbers on PCBWay.