Good job Dude.
I've suggested in a few threads the last year that many devices can be fixed this way, after discovering how to do it myself, and encountering micro-cracked solder points on several failed circuit boards. A little know how can save an awful lot of money. How much did a tad of solder cost vs. the hassle and expense of an entire new control, and in most cases you don't even need to add fresh solder - just remelt and coalesce the old.
Anytime you see unexplainable erratic device behavior, DC or AC, and ground connections are found clean and solid, there's a great chance the problem is an almost imperceptible crack in a solder joint on a circuit board somewhere. It's especially true for devices subject to cyclic heating and cooling, like TV-audio components in our front caps, convection microwaves, and others, but I even found it in a wireless computer mouse last fall.
It's far more common than we realize, and is now my main suspect when electric things go south. As you allude, it does take a quality magnifier to spot the cracks; I use the kind that fits over my head and has two eyepieces. I've caught solder cracks with that that got missed in cursory prechecks with a common handheld magnifying glass.
Joel
