I have had nearly every problem imaginable with pickup wiring. Weak signal, no signal, cuts out, thin, whatever. Obviously that doesn't say much about my soldering skills. :(
But, I have fixed the problem 99% of the time by resoldering everything very carefully, making sure each point is firm and properly grounded. It can be frustrating, but in my experience the problem is almost always a bad/improperly soldered joint or bad ground.