could be a lot of things. grounds are the quickest check.
pulling on stuff is never a good answer.
if anything, it could have shifted the cluster enough to get ground again.

you have to start somewhere. grounds are the best place to start.
especially since there really isn't a common between the headlight circuit and the gauges for power.
while the dash illumination runs through the light switch, power to the gauges goes through the key on.
it isn't likely a power SOURCE is your problem. rather common ground for the 2.