I have a 1970 Chevelle SS 396 with factory gauges. This past winter I removed the cluster to convert the clock to quartz and calibrate the gauges. Everything, with the exception of the clock worked when I removed them. Upon reinstalling the cluster everything works fine with the exception of the tach. I had the "Tachman" in Georgia do the work and he suggested that I check the (3) grounds coming off the cluster. As near as I can tell I have (2) grounds, the main plug attached to the cluster, and the power connection for the clock. Where should the (3) grounds come off the cluster? The tach does light up when the headlights are turned on. Could anyone tell me what might be wrong? Any Ideas would be greatly appreciated!