Weak contact on low voltage DC device causing noise. How?
It's arcing, low-voltage sparking, creates heat and the air expands... result, noise. 

You have a bad contact, possibly a broken solder joint.   It generates
heat as a result, and could cause serious damage.  So, best to repair it,
or get it repaired.    Jiggling it will make things worse, because
the parts may overheat AND come under stress at the same time.