Got it all buttoned up now. Sorry for the delayed reply - I left for holidays right after my last post and got back yesterday. Here’s a picture of the solder repair. Seems to be doing the trick. Most of the brown is flux that melted off and that I didn’t bother to clean off. The joint itself seems strong.

Not claiming that’s the prettiest solder joint - but you can see there’s lots of solder on the wire and the tab. Should do the trick. A little solder melted down and away from the connection, but that’s not going to hurt anything. When the module is connected the wires are pushed in, not away from the pump, so that should help too.

The white stuff on top of the red wire is just plastic chips from my chisel work. I brushed it off after.