Hi Keith, Welcome to the forum. Because all do not work, and a newly installed Tach also is non-operative, I would suspect a grounding issue. You or a service person should find where all the gauges are grounded and follow it back to check the source. Don't be fooled by the fact that your multi-meter shows a ground, it may show one but have such a poor contact it will not handle any current flow. Good Luck.
Peter - Doctor of Mixology