dry solder joint repair question

[Tomswork]

Baking soda works well to take the oxides of solder and many other parts rinse well. With good ipa or mild vinge

Edit
I have found mice pee inside of computers

Tom

[Plagued]

going to add my 2p.
With older electronics they tend to have large ground planes which can wick the heat away really quickly and make it hard to get a good joint.
I'm mainly saying this because there was a mention that the negative on the cap was problematic.
I've done a fair bit of work on old arcade boards and pinball (often repairing where someone had continued to up the temp of the iron and burned out the tracks trying to get something soldered) and found I had to use the same hot air and soldering iron setup with my Falcon for a lot of the negative terminals (heat the ground plane up around the solder point with air set to about 150c before soldering/desoldering).