It's possible your switch is just dirty. If the switch lever feel to have a positive stop for each selection, dirty would be a good possibility. It the switch lever feel loose and sloppy it most likely broken. If the whole switch is loose, you maybe have a bad solder joint.
If dirty, contact cleaner may get you back on track. Caution, contact clean can be dangerous to your finish.
The pick up sound very from how it's made. Mainly the windings. Pole adjustment in relation to the strings. Even how the magnetic field is protected from outside interference.
Hope this is helpful.
