The little box on the back of the dials,the voltage regulator,are very tempremental and when disturbed sometimes play up.Been through a few on mine over the years for various reasons.Another thing could be one of the fuses in the fuse box.Electrics on old cars are weird!
Also worth checking that you didnt damage the printed circuit board on the back of the dials where the main plug goes back into the dials,can be very fragile.