As hoped (and anticipated) the replacement BA6110 sorted out the problems I was having with x0xb0x #888.
Here’s another waveform photo like the one above, and here’s the bottom of the BA6110 with no-clean flux on it. Yes, there is a bit too much solder on pin 5, and possibly a couple others. No, it won’t hurt anything. Now all I have to do is finish tuning / adjusting things and then close it up.