[sdiy] unstable behaviour

[Rude 66]

boys and girls,

here's something i've been fighting with for a while. some things that i
build or modify work fine, but quite a few of them turn out to be unstable
in some way, especially circuit boards that i solder the parts in myself and
then connect to pots and switches on a front panel. i'm not talking
completely non-functional, but sort of working. sound cutting out, cracks,
pops, functions sometimes working, sometimes not.. that sort of thing. i'm
trying to figure out what's happening here.

i'm not the best solderer in the world, but what i do doesn't look any
better or worse than what i've seen from most. i've made sure there are no
solder bridges or loose wires. i've used the correct parts in correct ways,
yet still this occurs. i'm trying to figure out what does this. i can think
of 3 things:

- solder. how critical is solder in this matter? i know some kinds are
better than others, but they all basically do the job, right? would normal
basic solder do this?

- wire. i'm using basic stranded wire. would heat shrink around soldered
contacts help here?

-parts. how common is it for new parts to be broken? i've also used salvaged
or re-used parts like pots, switches, capacitors..

or is this sort of behaviour normal, and are you all too embarrassed to talk
about it? ;-)

thanks!

r./