i just got done rebuilding my dash on my 70 RR. i know its not a charger, but it looks the same to me, and dave is right. it just takes time , patience and a good light. i would reccomend removing the drivers seat for a more comfy work area. i didnt have 3 screws to remove the entire cluster from from the back though. heres how i did it:
i marked on a piece of paper the color of the dash light wires and what they do and where they go for re-assembly later
remove the speedo cable and drop the steering wheel about 1-1/2 inches so the bezel will come out easier
disconnect all the headlight,wiper,washer,dimmer connections....remove screws that are exposed in the bezel plate (6 or 7)
wiggle the bezel out on the tach side to expose the alt gauge wires and remove them
carefully wiggle the bezel completely out ( look in there before hand to make sure you removed all the dash light wires and whatnot.
it takes a little persuasion but it will come out
keep that piece of paper youll need it!
while the cluster is out, clean the circuit board pins.... theres a bunch of small screws that hold the bezel on. this is a great time to replace the twist in lights (3)
if by chance your gauges dont work, i have a full set of used ones that i replaced i have the speedo and a tic toc tach (tach works,clock dont)