Dear Brandon,

Good p.m. and may this find you well. A solder joint micro-crack can be far too small, to be seen with the unaided eye. Micro-cracks can be cured, by re-flowing the solder.

To do that, touch the tip of a 15-25 watt soldering iron to each joint. After 1-2 seconds, the solder will become shiny. At once remove the iron. The solder will revert to a dull grey. Be careful not to drag solder between contact points, as that will cause an electrical short.

You should do this for each joint on the circuit board.

The "brown crude" is flux, a material built into electrical solder (rosin core), to help the solder flow more readily. Flux does not harm the solder joint.

Hope this helps.

Yours faithfully,

spook