Ok - so I read some other posts about copper joints... but this is the brass fitting (to copper).
I unsweated the filler fitting. No problem. I used my inside wire brush and it seems to have worked, but the color of the brushed area is closer to the color of the solder than it is to brass. Is it normal for brass to lighten up in color or is that really just solder that's been brushed?
What should I do?