The increased brightness of one light could be a wattage thing, as there are a couple different ones to choose from...replace them both. This problem you're having sounds a lot like what I'm going through: I check the orange wire coming up to the dash and there's 12 volts when it's un-plugged, but as soon as I plug it into the circuit board, it goes down to 2volts. Not sure why it doesn't blow the fuse...I've ordered a new circuit board set out of desperation. The fuel gage is wacky also, there's a voltage limiter built into the fuel gage on my 66 Cuda. Since the gage get the current from the circuit board, there could be some connection.....but I'm guessing