My tic-toc-tach is not working. When I bought the car the tach did not work. I did a complete rewire under the dash and under the hood with American Auotwire harnesses. The tach still does not work. Ignition system is the Lectric Limited brand electronic ignition with a Mallory coil and that works well. The tach will bounce once in a while. What should I look for to make this work?